### Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

### 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?

# Divisible by 55

##### Age 11 to 14 ShortChallenge Level

Choose the digits $a$ and $b$ so that 227569$ab$ is divisible by 55. There are two possible answers!

This problem is taken from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.