You may also like

Adding All Nine

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!

Have You Got It?

Can you explain the strategy for winning this game with any target?

Counting Factors

Is there an efficient way to work out how many factors a large number has?

Ewa's Eggs

Age 11 to 14 Challenge Level:


Tomek accidentally knocked over Ewa's basket of eggs. Wishing to make amends he offers to pay as they are all broken.

Ewa, a mathematician, recognising a fellow mathematician's embarrassment, replies:
"I put the eggs into the basket in groups of 7 and noticed that I could easily have divided them into piles of 2, 3, 4, 5 or 6 and always have one left over."

What should Tomek offer to pay? (Eggs currently cost 95p a dozen)