Or search by topic
In a magic square, the three numbers in each row, in each column, and in each diagonal add up to the same number.
Complete this magic square.
An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.
Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!