What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

Can you count the number of blocks in the picture below?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

If two's company, and three's a crowd, then whats four and five ?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?