







Placing a sphere in a cylinder of water 
20160527 

From Fiona: Hi the question i have is, if I have a cylinder filled with water and the volume of the water is 150Pi what would the rise in the level of the water be if you put a sphere into the cylinder with a volume of 500/3Pi? Sorry if it's a bit long winded Answered by Penny Nom. 





A magic/math trick 
20091204 

From Valentin: What is the explanation for the following math trick: you think of any four digit number add those digits take that sum and subtract it from the first number then you say three of those new numbers in any order and the other person guesses the last digit.
How does he do it? Answered by Claude Tardif. 





A math trick 
20071210 

From Megan: I need to write a mathematical explanation of why this works!
Start with a four digit number. (a positive integer, and all digits can NOT be the same. At least one must be different)
Rearrange that four digit number.
Subtract the smaller 4digit number from the larger.
Now circel one digit. (canNOT be zero, because that is already a circle)
Now rewrite that number excluding the circled digit.
Compute the sum of the digits.
Now write down the next multiple of 9 that is larger than the sum.
Subtract the Sum from the multiple. (multiple  sum of digits)
Report Difference = to number circled.
The resulting number should be the number that originally circled. Answered by Penny Nom. 





Subtracting 5 from 25 
20011005 

From Melissa: How many times can you subtract the number 5 from 25? Answered by Leeanne Boehm. 





A Number Trick 
19981026 

From Brenda Meagher: I'm a 37 year old mother and i have returned to school for personal reasons. I was faced with this question. Choose any number less than 10, multiply it by 8547, then take your answer and multiply it by 13. I chose the number 8. 8547 x 8  68376 and 68376 x 13  205128 68376  888888 Any number chosen from 1 to 9 will result in the same form of answer.If the number two is used you will end up with 222,222.etc So my question is, is there another number that will results in the answers. Answered by Harley Weston. 

