Students+Contribution

Please post Mathematics quizzes and puzzles here. Please draw a line after each posting. Indicate your name after your posting (questions or answers).

Here's a great number trick: Step 1: Take a number from 1 to 9. Step 2: Multiply that number by 9. That is your new number. Step 3: Write down the numbers from 1 to 9, but without 8. (12345679) Step 4: Multiply your new number by the number in the above step. Step 5: See what you got! --- Kleon Ang

If: 1=5, 2=25, 3=325, 4=4325, 5=? ~Joshua XD

5=1

Cheok Feng :)

Haha nice trick question... ~Ryan Yeo

Homer Simpson needs to take Maggie, his dog and a jar of rat poison to the other side of the river. However, he can only bring one thing at a time. The dog cannot be left alone with Maggie or they will fight. Maggie cannot be left alone with the jar of rat poison or she will eat them.

How does he get all three of them to the other side of the river?~Nabilah 1)he takes maggie to the other side. 2)he goes to the other side 3)takes rat poison to the other side 4)takes maggie back 5)brings dog to the other side 6)go over to the side where maggie is 7)take maggie over ~VintVe

=Two Boys Cross a River= Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How? (Nicholas)

start on opposite sides?~ryan(correct) Are they even on the same side in the first place?-Laiyu I did not say they were or not.=D(Nicholas) seems like they are on opposite sides when you read the question.-laiyu

=Where Did the Dollar Go ?= Three friends have a nice meal together, and the bill is $25

The three friends pay $10 each, which the waiter gives to the Cashier

The Cashier hands back $5 to the Waiter

But the Waiter can't split $5 three ways, so he gives the friends one dollar each and keeps 2 dollars as a tip.

They all paid $10 and got $1 back. $10-$1 = $9

There were three of them 3 X $9 = $27

If they paid $27 and the waiter kept $2: $27+$2=$29

Where did the other dollar go? $30 - $1 = $29 (Nicholas)


 * Solution:** This is a trick question. Read it carefully.

Now let's do some prediction. Let's just say, that the cashier realised that you can't divide $5 into three, so he keeps $2 for himself and gives back the rest. See where it is going? The $2 is already included into the amount of $27 the three men paid! If follow the way i mentioned above...

Cashier realises the hassle, and keeps $2. Returns $3, which is split evenly. So, $30- $3 = $27. Therefore, no dollar is missing, and the problem is solved. ~Navneeth(correct)(I think)

**Where Did the Dollar Come From ?** Two friends have a nice meal together, and the bill is $25

The friends pay $15 each, which the Waiter gives to the Cashier

The Cashier hands back $5 to the Waiter

The Waiter keeps $3 as a tip and hands back $1 each

So, the friends paid $14 each for the meal, for a total of $28. The Waiter has $3, and that makes $31. Where did the other dollar come from? (Nicholas)

Multiply 999999999 x 111111111 without using calculator. Show your working with your answer.~Navneeth (from Math Olympiad)

999 999 999 x 111 111 111 =111 111 111 x 111 111 111 x 9 =12345678987654321 x 9 =111 111 110 888 888 889

seems like you used a calculator...o.O - i said no calculators allowed! (unless you sat down and did it on a piece of paper and solved it.)

An Audition was conducted to select one student to present flowers to the President. 150 students lined up in a row for the audition as follows: 1,2,3,4,5,......150 All students standing in odd positing falled out after the 1st round while those in even positions stayed. So, the following students remain behind after the 1st round: 2,4,6,8,.....150 For the 2nd round, the proccess is repeated. Those in the odd position fall out while those in even position stay. So, the following students remain behind after the second round: 4,8,12,.... The proccess of elimination continues until one student remains. If Peter wants to be the one to present the flower, which position should he occupy in the beginning? ( Xue Liang ) From: NMOS 2007 128?~vintve Right ~ Xue Liang

I think it is 128. 75, then 38, then 19, then 9, 5,3, then 1.

Read the sentence below and count the F's in that sentence.Count them ONLY ONCE. Do not go back and count them again. FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE OF YEARS. ---Nicole

There are six: first:line one, letter no.1 second:line one, letter no.9 third:line two, letter no. 6 fourth:line two, letter no. 13 fifth:line two, last letter sixth:line four, letter no. 15 note: letter refers to the Nth letter in the line excluding spaces.~VintVe

I think 6--Joel Not 3? I am certain it is three~ Yu fan

The answer is 6. But many people do not count the 'F's in the 'OF's. ---Nicole

The master's favourite vase is broken by one of the servants. The servants present at the scene give their own personal statement. A: "I did not break the vase." B: "The culprit is either C or D." C: "D did not break the vase." D: "Neither A nor B broke the vase."

One of the servants is lying. Assuming that only one person committed the dreadful dead, which servant is lying and who is the culprit? ~Yadanar

Was C the liar? Was it D who broke the vase? --- Kleon Ang I agree with Kleon. C is the liar and D broke the vase. --Kar Mun Yes, it can be the only possible outcome. If A and B was lying, D will also be together lying. But only one of them is lying, so the only one left is C.~ Yu FAn

If A was lying, it means he broke the vase. B said that the culprit is either C or D, so he is lying if A is lying. Since there can only be one liar, A must not be the culprit. If B was lying, it means the culprit is either A or B. We already know that A is not the culprit, so if B lied, he is the culprit. But D said that neither A or B broke the vase, so he must be lying, too. Since there are 2 liars, the culprit must then be either C or D. If C was lying, it means that D broke the vase. A's statement will be true, and so will B's. D's statement will also be true, thus D is the culprit and C is the liar.

~Ryan Yeo.

C is the liar, D broke the vase. This question is simple. Just assume that A is the culprit, then A lied, B lied, D lied. This is a contradiction. So A did not break the vase. If B is the culprit, then B lied, D lied. This is a contradiction. If C is the culprit, then no one lied. This is a contradiction.

SO, WITHOUT DOING IT FOR D YOU WOULD BE ABLE TO FIND OUT THE ANSWER. WELL,I CAN. C LIED AND D IS THE CULPRIT.

Two fathers took their sons fishing. Each father and son caught a fish, but when they returned, there were only 3 fishes. How could this be possible? --- Kleon Ang

A: there was a grandfather, a father, and a son - Matthew

Yes, right. --- Kleon Ang

Four students were arguing over the day of the week it should be.

A: Today is not Wednesday. B:Tomorrow will be Friday. C:It was Sunday yesterday. D: Both of you (referring to B and C) are not right. Only one student told the truth. What day of the week was "today" supposed to be? (Got it from a book. Answer in "Discussion". )Zheng Xian

is it wednesday? A, B & C were lying. D said the truth ~(Yong Ming) I agree.(Nicholas)


 * how many heaps?**

big ron is using his tractor to transport manure from his cowshed into two of his fields. after working all day he has created four heaps in his barley field and another three in his wheat field. there is so much manure in the cowshed that the following day he moves the same amount into each field again. how many piles of manure will he end up with if, on the third day, he puts all the heaps from the barley and wheat fields into a third field? (hint: think as logically as possible and read the question carefully) ~Ryan Heng is it 14?~VintVe The answer is: One big heap! (Isn't this a little cheating?) --- Kleon Ang oh right.

three pupils are asked to select four numbers under ten and then multiply them together. they all come up with the same answer even though they do not pick all the same numbers. how is this possible? ~Ryan Heng A:8x3x3x1=72 B:6x3x4x1=72 C:2x3x3x4=72 ~VintVe

Matthew- The sums are (not in order) __49 / 7 = 7__ __40 / 8 = 5__ __42 /6 = 7__ __7 x 2 = 14__ __4 +9 = 13__ __7+6 = 13__ __3 +1 + 3 = 7__ __6 x 5 = 30__ __5 x 0 = 0__ __3 + 3 = 6__ __1 + 3 + 2 = 6__ __3 + 3 = 6__ __56 / 8 = 7__ __(P.s / is divide)__

You can use the numbers 0 to 9 and +, -, x, /, = to fill in the blanks and solve the puzzle. (Ryan Teo)

It is pitch dark at night and four people need to cross the bridge. They have to light the path with a lamp but the fire can only last for 17 minutes. Only 2 people can cross the bridge at one time. Annie takes 1 minute to cross the bridge. Bob takes 2 minutes. Charmaine takes 5 minutes. Dorothy takes 10 minutes. How can they cross the bridge before the fire goes out? ~Yadanar

Assuming that whenever 2 people cross at a time, the faster one will wait for the slower one.

First, Annie and Bob cross with the lamp. 2 mins Then, Bob comes back with the lamp. Total: 4 mins Charmaine and Dorothy cross with the lamp. 14 mins. Annie comes back with the lamp. 15 mins Bob and Annie cross together with the lamp. Total time taken: 17 mins (Bingo!)

~Ryan Yeo. (Correct)

Of three men one man always tells the truth, one always tells lies, and one answers yes or no randomly. Each man knows which man is who. You may ask three yes/no question to determine who is who. If you ask the same question to more than one person you must count it as question used for each person whom you ask. What three questions should you ask? ~Yadanar (This requires a lot of working. Try to use factorial for the number of different possibilities.)

Use the numbers 1 through 16 to complete the equations. Each number is used only once. Each **row** is a math equation. Work from left to right. Each **column** is a math equation. Work from top to bottom. ~Yadanar

How can I get the answer 24 by only using the numbers 8,8,3,3. You can use the main signs add, subtract multiply and divide. from http://www.mathsisfun.com/puzzles/24-from-8-8-3-3.html (Nicholas Tan)

the ans is obvious: 8x8+3-3 (bryan) (wrong)

wait isn't 8x8= 64+3-3=64-Yu Fan

I got it! Ans: ([8 x 3! ]÷3)+8 =8 x 6÷3+8 =8 x 2+8 =16+8 =__24__ ~Cheok Feng(correct) I thought we could only use add, subtract, multiply and divide?-laiyu

I got it too! Ans: 8 x 3! - 8 x 3 = 8 x 6 - 8 x 3 = 48 - 24 = __24__ (Bingo!)

~Ryan Yeo.(correct)

you CAN use add, subtract, multiply and divide. not only.(Nicholas)

SHIPS from http://www.mathsisfun.com/puzzles/ships.html There are 5 ships in a port: 1. The Greek ship leaves at six and carries coffee. 2.The Ship in the middle has a black chimney. 3. The English ship leaves at nine. 4. The French ship with blue chimney is to the left of a ship that carries coffee. 5. To the right of the ship carrying cocoa is a ship going to Marseille. 6. The Brazilian ship is heading for Manila. 7. Next to the ship carrying rice is a ship with a green chimney. 8. A ship going to Genoa leaves at five. 9. The Spanish ship leaves at seven and is to the right of the ship going to Marseille. 10. The ship with a red chimney goes to Hamburg. 11. Next to the ship leaving at seven is a ship with a white chimney. 12. The ship on the border carries corn. 13. The ship with a black chimney leaves at eight. 14. The ship carrying corn is anchored next to the ship carrying rice. 15. The ship to Hamburg leaves at six. Which ship goes to Port Said? Which ship carries tea? (Nicholas Tan)

Nicholas, I have a question: Will there be 2 ships carrying tea or just one? ~Cheok Feng Isn't this a variation of Einstein's puzzle?~VintVe There can be two. It IS Einstein's puzzle. (Nicholas Tan) ANS: The Spanish ship goes to Port Said and the French ship carries tea ~Nabilah(correct)

1) What is the closest possible relationship between the Defendant and the Judge if the Defendant's Brother-in-law's only Sister's Husband is the Father of the Son of the Judge?

They are the same person, or are brother-in-laws.(Nicholas Tan) (wrong)

The Judge is the Defendant's brother-in-law's brother-in-law. ~Nabilah (wrong)

//It's the brother-in-law's only sister//. Is it? I just drew a family tree and the Judge should be a female. She is wife of the Father and other sister of the Defendant's sister's husband. ~Yadanar (wrong)

The Judge is the wife of the Defendant? (Amelia) (correct)

2) Find the value of 1-(1-(1-(1-(1-(1-(1-(1--X)

X- Topaz Tan (correct)

X. That was so obvious! ~Joshua XD

3) A, B, C and D were suspects for shoplifting. Each one of them made one statement each. Only one of their statements were false. Find the shoplifter if the statements stated were below.

A: B did it B: D did it C: I didn't do it D: B lied when he said that I stole it.

//B's statement should be false and B should also be the shoplifter.// //Method:// //If A was lying then it could not be B. Then B said that D did it and if it was true that D should be the shoplifter but D said he didn't do it so A was telling the truth.// //If D was lying then since B said that D did it, D should be the shoplifter but A said B was the shoplifter so this is too wrong.// //And as for C if he was lying then he would be the shoplifter but all the others statements contradict that. ~Yadanar (correct)//

This is what I think: Supposing A was right and B did it. Then B would be the one who was lying. WhenC said he didn't do it, he was right because B was the one who did it. And D would also be telling the truth as he didn't do it and B was the one who did it. Conclusion: B is the shoplifter. (That's easy. I solved it in three minutes. For once I managed to solve a puzzle in such a short time.) ~Lisa

B is lying and B is the shoplifter ~Joshua XD

4) At first, 25% of Tom's money was the same as 33 1/3% of Lily's money. Lily's father gave her $80 later, while Tom spent $325. In the end, Lily had 2 1/2 times as much money as Tom. a) How much money did Tom have at first?

5) Ben and Jerry had some money. If Ben spends $45 per day and Jerry spends $15 per day, Ben would have $120 by the time Jerry spends all his money. If Ben spends $15 per day and Jerry spends $45 per day, Ben would have $1080 when Jerry spent all his money. How much money does each of them have at first? (RGPS P6 Prelim 2009)

Jerry had $360 and Ben had $1200 - Topaz

6) Minah had some money at first. She spent it all on 3 stores. In each stall, she spent $2 more than half of what she had when she entered the store. (Rosyth question) a) How much money did she spend at the last store? b) How much money did she have at first?

~ Ryan Yeo (These questions are taken from my tuition center)

-For question 3 I think the answer is (B) -Daren (correct) - I also think it is B, I used guess and check. (I found the answer, then I realized that Daren already did it) (laiyu) (correct) A round of applause for Daren!!! But would you kindly show your working? ~Ryan Yeo I used the same method as Yadanar, it is like assuming that someone is the shoplifter and checking the facts -Daren - For question 6 a) I think the answer is $68 and for question 6 b) I think the answer is $12. - Jia Wei (wrong and wrong) - Is the answer for 6 a) $4 and the answer for 6 b) $48? I am not so sure... I read the question a bit wrongly last time... (Your answer for 6a is correct but your answer for 6b is not quite right... Try again!)

-For Question 5 I think the answer is... 45÷15=3 45 x 24=1080 1080+120=1200 15 x 24=360 1200-1080=120 120÷15=8 360÷45=8 So Ben: __**$1200**__ and Jerry: **__$ 360__** ~Nabilah (correct and correct)

I think the answer for question 6a is $4 and the answer for question 6b is $28. ~Jiajun (Correct and correct)

There are five people - Holly, Cameron, Julieanne, Alex and Jackie. Each one stole a special cookie of their favourite brand which was kept in a jar. Each person ate it in a particular place and drank their flavoured milk with it.

Andre Ng(from [])
 * Jackie is next to the person who eats on the lounge.
 * Arnotts brand cookies are kept in a round jar.
 * The person beside Cameron eats cookies at a table.
 * The person who eats Oreos eats in the closet
 * Julieanne likes Paradise brand cookies
 * The person who drinks banana milk is in the middle and owns a tall jar
 * The first person likes vanilla milk
 * Holly is the person on the far right
 * The person who eats in the bedroom drinks strawberry milk
 * The person who owns the tall jar is next to the person who owns square jar
 * Cameron drinks caramel milk
 * The person who likes the Dick Smith brand is next to the person who likes the Coles brand
 * The person who likes the No Frills brand is next to the person who owns a round jar
 * The person who stole the 100s and 1000s cookies is next to the person who owns the brass jar
 * The second person from the right eats No Frills brand and is next to the person who owns a round jar
 * The first person on the left stole the choc chip cookies
 * The person who eats Dick Smith brand is next to the person who eats Paradise brand
 * The second from the left has a brass jar
 * Julieanne is to the right of the person who drinks strawberry milk
 * The person who drinks chocolate milk does it at the table
 * The Paradise brand cookies are eaten in the kitchen
 * The person who eats Tiny Teddies doesn't keep them in a round jar
 * The Coles brand cookies are kept in a mini sized jar
 * ~ Person || Alex || Jackie || Julieanne || Cameron || Holly ||


 * ~ Flavour || Vanilla || Strawberry || Banana || Caramel || Chocolate ||


 * ~ Cookie Jar || Mini || Brass || Tall || Square || Round ||


 * ~ Brand || Coles || Dick Smith || Paradise || No Frills || Arnotts ||


 * ~ Cookie || Choc chip || Tiny Teddies || 100s and 1000s || Oreos || Anzac ||

~josh (sorry, alignment problem) ||
 * ~ Place || Lounge || Bedroom || Kitchen || Closet || Table

1.Every month, a girl gets allowance. Assume last year she only had $4, and kept it up to now. Then she spends 1/2 of her money on clothes, then 1/3 of the remaining money on games, and then 1/4 of the remaining money on toys. After she bought all of that, she had $7777 left. Assuming she only gets money by allowance, how much money does she earn every month? (This should be rather easy) (From [])

7777÷ 3=2592.333333 2592.333333 x 12=31108 31108-4=31104 31104÷ 12=2592~Nabilah I think it's $2592 every month.~Nabilah

2. Three men walk into a motel and ask for a room. The desk clerk says a room is $30 so each man pays $10 towards the cost. Later, the clerk realizes he made a mistake, that the room should have been $25. He calls the bell boy over and asks him to refund the other $5 to the three men. The bellboy, not wanting to mess with a lot of change dividing the $5 three ways, decides to lie about the price, refunding each man $1 and keeping the other $2 for himself. Ultimately each man paid $9 towards the room and the bellboy got $2, totaling $29. But the original charge was $30, where did the extra $1 go? (From []) -Daren -$25 + $3 =$28 $28 + $2 = $30

By calculating that $30 - $3 = $27, you are already excluding the $1. ~Ryan Yeo.

Each man pays $9 after that since they got their $1 refunded. So the man pay $27. But in that $27, the bell boy's $2 is included. The $5 was supposed to be distributed among 3 man but they each got $1 and the bell boy, $2. Thus, the $2 was supposed to belong to the 3 man and it is counted in the $27. ~Yadanar

1. Continue the pattern: __M T W T__ _ _ _

M T W T //F S S// ~Yadanar

-Why? I don't get it. ~Ryan Yeo.

Monday, Tuesday, Wednesday....Saturday and Sunday --- Kleon Ang

2. Draw a square with 3 lines.

---Kleon Ang

~Yadanar

-(Yadanar, I'm not sure how this is a square. Can you explain?) ~Ryan Yeo.

You're supposed to draw a square, and it has to have three lines too. So a square with three lines in it :) I asked my father that. ~Yadanar

~Oh, that's quite tricky. ~Ryan Yeo.

Yes, the square with 3 lines is right :-) --- Kleon Ang

Wow. I spent half an hour trying to figure this question out and it was only when I finally got the answer that I realized others have already done so long ago. But I got the same thing anyway. ~Lisa

A and B were on a hiking trip, on their way, they met a traveller(C). They decided to go hiking together. After hours of hiking, they decided to go for a break under a shady tree. A took out 7 pieces of sandwiches, while B took out 5 pieces of sandwiches. They shared it among the three of them equally. At the end of the trip, the traveller takes out 12 pieces of biscuits. He gave 7 to A and 5 to B. Is this way of distribution fair? Why?

Andre Ng No. A gave C three times as many sandwiches as B. So, A should take 9 bicuits whereas B should take three biscuits to have a fair distribution.~Nabilah

1.While three __wise__ men are asleep under a tree a mischievous boy paints their foreheads red. Later they all wake up at the same time and all three start laughing. After several minutes suddenly one stops. Why did he stop?

That man notices that the others are also laughing at him.~Ryan Yeo. (close. actually, the man realised that his forehead was also painted-laiyu)

But if they are all wise, wouldn't all of them stop laughing eventually?~Nabilah ( they would, but maybe the man realised first?-laiyu) {Maybe all of them are wise but one is the wisest so he stops laughing first. ~Yadanar} [I think so-laiyu]

If they were wise men, they would stop laughing. As all three are laughing, one soon realises that he acting actng like the other two, and wise men know that they should copy others but do it their way.-caleb []

2.Alan can finish packing a certain number of boxes in 4 hours. Barry can finish packing the same number of boxes in 3 hours. If Alan and Barry work together for 5 hours and in that time, Barry packed 600 boxes, how many boxes did Alan pack? (laiyu)

Alan packed 450 boxes ~ josh (correct, please show working. By the way, it is a one-step working-laiyu)

600/5=120 120 x 3 =360 360/4 =90 90 x 5 =450 Ans: 450(Calebho)

__One of my favourite problem:__

__On a table, there is one 40 ml cup and one 70 ml cup. John only needs 20 ml of water. Can you help him obtain 20 ml with just the 2 cups? (Estimation is NOT the answer)__ __~ Cheok Feng__

__(I think I accidentally deleted it while I put my posted my question, so I put this question back, it is not my question-laiyu)__

__-- I have a question. Do the cups contain water, or do you have to obtain 20ml of water elsewhere? ~Ryan Yeo.__ __You have an unlimited supply of water.~Cheok Feng__

__First, you fill the 70 ml cup to the brim and pour the water from the 70 ml cup to fill the 40 ml cup (so that you have 30 ml of water left in the 70 ml cup) and empty the 40 ml cup. Then you transfer the 30 ml of water from the 70 ml cup to the 40 ml cup. After that, you fill the 70 ml cup to the brim again and pour the water to fill the 40 ml cup to leave 60 ml of water in the 70 ml cup. Finally, you empty the 40ml cup full of water and fill it full once more by pouring water from the 70 ml cup, filling the 40 ml cup to the brim and leaving the target of 20 ml of water in the 70 ml cup.~Jiajun (correct)__

In a certain bank the position of cashier, manager and teller are held by Allan, Barry and Simon, though not respectively. The teller, who was an only child, earns the least. Simon, who married Allan’s sister, earns more than the manager. What are the positions that Allan, Barry and Simon fill? ~ Nabilah

__Simon is the teller, Allan is the manager and Barry is the cashier, by elimination process. ~Ryan Yeo. (Wrong)__ __But if Simon is the teller, how can he earn more than the manager when he earns the least? ~Yadanar__ __Whoops, sorry. So Barry is the teller, Allan is the manager and Simon is the cashier. ~Ryan Yeo.__

__Alan - Cannot be the teller (Has a sister)__ __Simon - Cannot be the manager (Earns more than the manager), cannot be the teller (Simon is supposed to earn the most)__

__Simon - Cashier__ __Alan - Manager__ __Barry - Teller ~Yadanar__

__Simon is the cashier, Allan is the manager and Barry is the teller. ---Nicole__

If you have a GST, 10 %service charge and 20%discount for a $100 restaurant bill, it doesn't matter if you add service charge first, or GST first, because it will all end up the same. Anyone knows why? Posted by Joel on 2 June 2010 at 7.25 pm

__A (Discount first)__ __100-100*20%=80__ __GST is 7%__ __10%+7%=17%__ __80+80*17%=93.6__

__B (GST n Service charge first)__ __100+100*17%=117__ __117-117*20%=93.6__

__~josh (try it yourself, on the cauculator)__

__I found out a way to calculate some numbers really easily!__

__An example: 75x95, take 7 as A, 9 as B__ __the method is: 1. AxB, in this case is 7x9=63. 2. (A+B)x0.5, in this case it is 8. 3. Add 8 to 63=71. 4. Multiply the last digit of both numbers, in this case 5x5=25. So, put 71in front of 25 and you get 7125! This method does have a restriction, the last two digits have to add up to 10, and the sum of the first digits has to be even. This is posted by Joel on 2 June 2010 at 4.40pm.__

1. In a fishball factory, Machine A was turned on first and it produced 400 fishballs. It was turned on afterwards. For every 3 fishballs A produced, B produced 5 fishballs. B produced 40 less than 3/8 of the fishballs produced. How many fishballs were produced in total? (Hint: There is a redundant clue here. If you can find the redundant clue, the question should be easy.)

1. 400-40=360 5u=360 1u=360/5=72 8u=72x8=576 (Ryan Teo) (correct)

2. (I know this question will sound nonsensical, but it is mathematically solvable)

If a goose and a half can lay an egg and a half in a day and a half, how many eggs can seven geese lay in six days? ~Ryan Yeo.

1 goose: 1 egg -- One day and a half 6 geese: 6 eggs -- One day and a half 4 One days and a half in six days 6 x 4 = 24? ~Yadanar (wrong) {I think I made a careless mistake. Should be 7 geese}

Is it 28? (7 x 4) ~Jiajun (correct but can you show detailed working?)

1 goose = 1 egg -- 1 1/2 day 6 divide 1 1/2=4 so 7 geese x 4 = 28 ---Nicole

This is how you calculate the 11 times table for 2-digit numbers.

Eg. 16 x 11

Add the 2 digits of 16. Place the sum between the digits of 16. In other words,

1 (1+6) 6 176

~Ryan Yeo. thx a lot, i didnt realise that. there's a restriction actually. the digits of the number which is going to be multipled by eleven must add up to a one-digit number. ~ yong ming Actually, no. For example, when calculating 19 x 11, you add 1 + 9 = 10, then you place 0 in the middle and add the 1 to the hundreds place, and it becomes 209. ~Ryan Yeo. me neither. ~ Cheok Feng

i realized that, works.-caleb

I realised this very long ago! ~Joshua XD

Vincent bought a second-hand car for $48000. He paid $3800 as deposit and the rest by monthly installments for 6 years. However, after paying installments for 4 years, he decided to settle the rest of the balance in 1 year. What is the new monthly installment that Vincent has to pay in that one year? (Pls show working)--Kar mun

48000-3800=44200 44200/(6 x 12) =613.8888889 613.8888889 x 2=1227.777778=1227.80

in the last year, he had to pay twice of what he paid in the previous year as 6-4=2 ans:$1227.80

Two people, A and B, had the same amount of money at first while C had a seventh of what they had in total. After A and B went shopping, A had spent a total of $4531 on a television set while B had spent a certain amount on the same television set that A had bought along with 2 microwave ovens. If the ratio of money that A and B had left was 47:45 and the ratio of the money that A spent compared to the total amount of money they had at first was 23:140, how much money did C have? ~Jiajun

There were 10 stacks of gold bars with 10 gold bars in each stack (Meaning that there are 100 gold bars). However, one stack of gold bars (10 gold bars) is fake and a fake gold bar weighs less than a normal gold bar. Taking that you ONLY have an electronic weighing scale that you can use ONCE, how can you locate the stack of fake gold bars? (You cannot weigh the gold bars with your hand or anything else)

~Jiajun

Taking it that the fake bar weighs 1g less:

Take one bar from the first stack, 2 bars from the second stack etc. If the weighing scale's reading is 7g less than the normal weighing scale, it is the 7th bag, and so on. ~Ryan Yeo. (Correct)

What is it that you can see with the naked eye, seems to have no weight and yet the more of them you put into an empty container, the lighter the container becomes? (Amelia)

A Hole ~Ryan Yeo. Is it a hole? -may yen

it s a hole.caleb i think

Air? ~ Xue Liang

These are the answers to the questions I posted so far as of 4th June 2010 at 6:13 pm.

~Ryan Yeo

1. The Lord of the Manor has been murdered. The visitors to the manor were Abbie, Bobby and Colin. The murderer was the visitor who arrived at the manor later than at least one of the other two visitors. One of the visitors was a detective who arrived at the manor earlier than at least one of the other two visitors. The detective arrived at midnight. Neither Abbie nor Bobby arrived at the manor after midnight. The earlier arrival of Bobby and Colin was not the detective. The later arrival of Abbie and Colin was not the murderer. Who then was it who committed the murder?

2. A group of children visited a farm and saw: a) One animal with half as many letters as its plural b) One animal with half as many letters as its young c) One animal with the same sound as its plural When the group moved further on they saw the same again but each animal was different. What are the animals? ~Amelia a=ox b=pig/cat c=sheep ~VintVe (is it correct?)

1.A company sells detergent in three different sizes: small, medium and large. The medium size costs 50% more than the small size and contains 20% less detergent than the large size. The large size contains twice as much detergent as the small size and costs 30% more than the medium size. Rank the three sizes in terms of the value-for-money, from highest value to lowest value. ~Vint Ve Taken from 2009 NUS high maths olympiad. 2. **THE SMILEYS PROBLEM** Challenge: Try to connect the three smiley faces to the houses using lines which CANNOT overlap, cross over, etc. It doesn't matter if they curve around, they're supposed to. PS. it was supposed to be called the utilities problem and it was supposed to be impossible. PSS ALL the smileys are supposed to be connected to ALL the houses using lines.~VintVe does anybody want me to post the solution yet, or do you want to complete it yourself _ __Cannibals ambush a safari in the jungle and captured three men. The cannibals give the men a single chance to escape uneaten. The captives are lined up in order of height, and are tied to stakes (not sticks). The man behind can see the backs of his two friends; the man in the middle can see the back of the man in front; and the man in front cannot see anyone. Hats are worn over the men without them knowing what the colour of their hat is. After that, they have to guess the colour of their hat. The man behind and in the middle said,"I don't know." However, the man in front knew what the colour of his hat is. Suppose there were only three black hats and two white hats, how did the man in front know? ~ yongming__ __from : []__

A→front guy B→middle guy C→guy at the back

C said I don't know, so A & B know that both are wearing black, or one is black, one is white . (If both were white, C would not have said I don't know, but would have said 'black'.) B also said I don't know, so A knew that he himself was wearing black. (If A was white, B would have said 'black'. But B saw a black hat, so his own hat could be either black or white.) ~Cheok Feng (correct)

Is it because the guy in the middle told him? Zheng Xian (wrong)

He knew because when the person at the top saw the hats, he was able to tell his, enabling the 2nd last man to know the color of his hat, and thus enabling the middle guy to know the color of his hat and so on.- Matthew (dont get wat u say) E.g Man at back red 2nd back sees(and hears) 2 red and 2 black, concludes his is red middle sees(and hears) 1 black and 3 red, concludes his is black 2nd front sees (and hear) 2 red and 2 black, concludes his is red 1st sees (and hears) 1 black and 3 red, concludes his is black - Matthew _ 1 11 21 1211 111221 312211

What the next sequence???????~ josh

__13112221 ~ Zheng Xian(I know, from AMEC)__

Matthew- 1. Compute 11 111 111 x 99 999 999 without using calculators. A: 11 111 111 x 99 999 999 =11 111 111 x 11 111 111 x 9 = 9(11 111 111^2) = 9 x 123456787654321 -( for how i get product w/o calculators, scroll down) = 1111111088888889 ~VintVe =)

11 x 11 = 121 111 x 111 = 12321 1111 x 1111 = 1234321 11111 x 11111=123454321 see the pattern? ya..... 111111x111111=12345654321 1111111x1111111=1234567654321 11111111x11111111=123456787654321 111111111x111111111=12345678987654321 here is when things get a bit blur 1111111111x1111111111=1234567900987654400 11111111111x11111111111=123456790120987650000

~josh(is it correct?)(the two last few?) actually 11111111111x11111111111=1234567890120987654321 cos if u simplify everything its: 11111111111x1+11111111111x10+... and so on, and since 1x1 is 1, so it should end in a 1 and not 0.~vintve

=
1. S-M-H-D--M-- , and  stands for letters in the series. a)Find all the , ,  b)Explain 2. In the figure shown, the matchstick forms to make a dog. a) moving only two matchsticks, make the figure such that the dog's head is facing the bone b) moving anly two matchsticks again, make the dog face the bone. However, you cannot move the tail. c) while the dog is looking at the bone, sadly it got run over by a double-decker bus. moving only two matchsticks, show it dead after the run-over. PS. it would help if you use this, edit it, then post it: ~VintVe

Jia Wei

1) A, B, C, D, E, F, G and H took part in a long race. After the race, they all made two statements.

A said,"B is the first; G is slower than me." B said,"E is slower than G; H is faster than D." C said,"H is slower than me; F is behind D." D said,"I am the second; C is not the last." E said,"I slower than F; I am faster than B." F said,"A got first or second; E is not the fourth." G said," Two people crossed the line at the same time, D is slower than me." H said,"A is not in front of me; B is slower than D."

Out of the sixteen statements, only one of them is correct. Which one is correct? What is the ranking order?

2) There is a circle within a square. The circle is drawn to its maximum size. The area of the square is 200cm square. What is the area of the circle?

1) If **x**2 + **y**2 = 100, and **xy** = 18. If **x** is bigger than **y**, find the value of **x** - **y**.

Justin

1.The cost of publishing a novel for a publishing house has gone up by 10% as compared to the year before but the publisher wishes to maintain the selling price of the novel. As a result, the profit for each novel drops by 40%. The number of books bought however, increases by 80%. What is the percentage of the increase in the profit? (solution is in the disscusion page.) May Yen

1) John wanted to find out the mass of three different fruits at a fruit stall. He asked the salesperson. However, the salesperson was stubborn and would only give him some clues. Can you help John figure out the mass of each fruit?

This was what the salesman said:

2 Watermelons and 1 Durian weigh 8 kg. 2 durians and 1 papaya weighs 5 kg 1 watermelon and 1 papaya weigh 4 kg.

1) Watermelon ~ 3kg Durian ~ 2kg Papaya ~ 1kg ~ZH --- The Bonsai Problem  Person A and Person B are good friends. Person B owns a Bonsai shop. Person A wants to buy a pot of Bonsai. Because Person A is his friend, Person B decides to give him a discount.  This is what he says:  “Last month, the price of this pot of Bonsai of which you want to buy was $200. Last week, after reshaping and trimming, its price went up by 10%. But since you have been such a good friend to me, I’ll give you a 10% discount.”  What is the price of the pot of Bonsai now?  $198~vintve  $198?  ~Joshua XD

The Two Witnesses A crime was committed and there were only two witnesses. One witness always tells the truth whereas the other always lies. When questioned, Witness 1 said that Suspect A committed the crime, but Witness 2 said Suspect B did it. Who should the policeman trust?

The Matchstick Problem How can I move two of the matchsticks so there is nothing left?

-Lisa

Show your Working.

2) George wanted to find out the population of a place. He asked a resident who was just leaving that place. This was what the resident told him:

"I went to that place and I met a man with 7 wives. Each wife carried seven sacks, and in each sack there were seven cats, and each cat had seven kittens."

Assuming that he and the people he met were the only residents of that place, How many people and animals were there, excluding George?

ans:351 (wrong)

Ans: including the resident, 401~Nabilah

3) "Two down, three to go for Gold".

Ronald Susilo said this in the knock-out tournament of the 2004 Olympics.

Using the clues above,

a) How many players were participating in the tournament? b) How many matches were there in all?

~Ryan Yeo.

32 people, 31 matches ~Joshua XD

Calculate these without calculator. Show your workings: 1) 3231 x 3231 - 3230 x 3232 2) 12341234 x 1233 - 12331233 x 1234 ~VIntVe

2) 12341234 = a 12331233 = b (wrong)

Answer by vintve: 1) 3231 x 3231 - 3230 x 3232 =3231 x 3231 - 3230 x (3231+1) =3231 x 3231 - (3230 x 3231 + 3230 x 1) =(3231 x 3231 - 3230 x 3231) - 3230 =3231 - 3230 =1 2) 12341234 x 1233 - 12331233 x 1234 =10001 x 1234 x 1233 - 10001 x 1233 x 1234 =0

1) a worker was enployed to put up the unit number on each bungalow for 79 bungalows. the unit number is made up of individual digit pltes such that the unit number 13 would consqst of digit 1 and 3 plates. a:which digit plate was usd the least?

b:how many 5 plates were used?

c:how many plates did he use altogether?

pls do working-caleb

1 number plates x 17 2 number plates x 17 3 number plates x 17 4 number plates x 17 5 number plates x 17 6 number plates x 17 7 number plates x 17 8 number plates x 7 9 number plates x 7 0 number plates x 6

a) The 0 number plate was used the least.(correct) b) 17 number 5 plates were used.(correct) c) 17 x 7 = 119 7 x2 = 14 6 + 14+ 119 = 139 He used 139 plates altogether( error) ~ Xue Liang

Solution __a) 0__ __b) 17 plates__ 15 25 35 45 65 75 50 to 59=10 10 + 7 = 17 __c)149__ 1 to 9 =9 10 to 19=10 x 2 =20 20 to 69=50 x 2 =100 70-79=10 x2 =20 9 + 20 +100 +20 = 149

How did he do it

John told Tom that he could mind read. He told Tom to choose a number from 2 ~ 9, then double the number. Next, he told Tom to add 14 then divide the number by 2. And finally, subtract the number he chose previously. John told Tom that his answer is 7. How did he do it? ~ZH __the answer is always 7:__ __algebra: treat a as the number Tom chose__ __first step:__ __2a__ __second with third step:__ __(2a+14)/2=(2a/2)+(14/2)=a+7__ __last step:__ __a+7-a=7 ~VintVe__

pi song: [] easy way to memorize it~vintve

But I memorized up to 31 decimal places: 3.1415926535897932384626433832795...

Four people come to a river in the night. There is a narrow bridge, but it can only hold two people at a time. Because it's night, the torch has to be used when crossing the bridge. Person A can cross the bridge in 1 minute, B in 2 minutes, C in 5 minutes, and D in 8 minutes. When two people cross the bridge together, ... they must move at the slower person's pace. Your job is to get all four people across the river, in 15 minutes. The question is, can you?

~Jeremy~ :)

Ans:

A and B cross, (2 mins) B comes back with lamp, (total: 4 mins) C and D cross, (12 mins) A comes back with lamp, (13 mins) A and B cross again. (15 mins) ☺

~Cheok Feng

I never knew that pi can be up to a million digits... If you want to know the digits pi contains, click [|here]. ~Ryan Yeo.

Ooh... that is giving me a nasty headache...~Cheok Feng

Erm..Ryan, pi has infinite amount of digits, it never ends~josh

Aya, now you told me, I had better not do anymore research about pi. How did people come up with this anyway? ~Ryan Yeo.

this is a river question. There is a policeman, a thief, two daugthers, two sons, a father, and a mother You are supposed to get everybody aross the river, now, the rules... There is a raft. the raft can only carry 2 people Only the policeman, mother and father can operate the raft The thief cannot be with the family without the policeman the sons cannot be with the mother without the father the daugther cannot be with the father without the mother The thief can be left alone without the policeman but no family members must be on the same side. ~josh


 * ~ Level ||~ Experience ||~ Level ||~ Experience ||~ Level ||~ Experience ||~ Level ||~ Experience ||
 * 120 || 85,560 || 90 || 36,090 || 60 || 10,740 || 30 || 1,410 ||
 * 119 || 83,436 || 89 || 34,901 || 59 || 10,215 || 29 || 1,280 ||
 * 118 || 81,349 || 88 || 33,739 || 58 || 9,709 || 28 || 1,159 ||
 * 117 || 79,296 || 87 || 32,603 || 57 || 9,219 || 27 || 1,046 ||
 * 116 || 77,279 || 86 || 31,493 || 56 || 8,747 || 26 || 941 ||
 * 115 || 75,296 || 85 || 30,408 || 55 || 8,291 || 25 || 843 ||
 * 114 || 73,347 || 84 || 29,349 || 54 || 7,851 || 24 || 753 ||
 * 113 || 71,432 || 83 || 28,315 || 53 || 7,427 || 23 || 670 ||
 * 112 || 69,552 || 82 || 27,306 || 52 || 7,020 || 22 || 594 ||
 * 111 || 67,704 || 81 || 26,320 || 51 || 6,627 || 21 || 523 ||
 * 110 || 65,890 || 80 || 25,360 || 50 || 6,250 || 20 || 460 ||
 * 109 || 64,108 || 79 || 24,422 || 49 || 5,887 || 19 || 401 ||
 * 108 || 62,359 || 78 || 23,509 || 48 || 5,539 || 18 || 349 ||
 * 107 || 60,642 || 77 || 22,618 || 47 || 5,205 || 17 || 301 ||
 * 106 || 58,957 || 76 || 21,751 || 46 || 4,885 || 16 || 259 ||
 * 105 || 57,303 || 75 || 20,906 || 45 || 4,578 || 15 || 221 ||
 * 104 || 55,681 || 74 || 20,083 || 44 || 4,285 || 14 || 187 ||
 * 103 || 54,090 || 73 || 19,282 || 43 || 4,005 || 13 || 157 ||
 * 102 || 52,530 || 72 || 18,504 || 42 || 3,738 || 12 || 132 ||
 * 101 || 50,999 || 71 || 17,746 || 41 || 3,482 || 11 || 109 ||
 * 100 || 49,500 || 70 || 17,010 || 40 || 3,240 || 10 || 90 ||
 * 99 || 48,029 || 69 || 16,294 || 39 || 3,008 || 9 || 73 ||
 * 98 || 46,589 || 68 || 15,599 || 38 || 2,789 || 8 || 59 ||
 * 97 || 45,177 || 67 || 14,924 || 37 || 2,580 || 7 || 47 ||
 * 96 || 43,795 || 66 || 14,269 || 36 || 2,383 || 6 || 37 ||
 * 95 || 42,441 || 65 || 13,633 || 35 || 2,196 || 5 || 28 ||
 * 94 || 41,115 || 64 || 13,017 || 34 || 2,019 || 4 || 21 ||
 * 93 || 39,817 || 63 || 12,420 || 33 || 1,852 || 3 || 15 ||
 * 92 || 38,548 || 62 || 11,842 || 32 || 1,696 || 2 || 10 ||
 * 91 || 37,305 || 61 || 11,281 || 31 || 1,548 || 1 || 4 ||

This is a table showing the levels of a person playing a game and the experience gained if they use a special lamp. Your job is to find out the relation between the level and the experience gained. Express your answer in terms of n. ~Jeremy~