The four digits 2, 3, 8 and 9 are placed in the boxes so that when both two-digit numbers are added, the sum is as large as possible. What is this sum?
There are 5 red, 5 green and 5 yellow jelly beans in a jar. How many would you need to take out of the jar without looking to make sure that you have removed at least two of the same colour?
The sum of the seven digits in Mario’s telephone number is 34. The first five digits are 73903. How many possibilities are there for the last two digits?
In this diagram there are four lines with three circles each. Place the numbers from 1 to 7 into the circles, so that each line adds up to 12. Which number must go into the circle at the centre of the diagram?