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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?

AB Search

Age 11 to 14 Short
Challenge Level

The five digit number A679B, in base ten, is divisible by 72. What are the values of A and B?

You can find more short problems, arranged by curriculum topic, in our short problems collection.