You may also like

Off the Cuff

Can you work out the ratio of shirt types made by a factory, if you know the ratio of button types used?

A Leg to Stand On

Can you work out the number of chairs at a cafe from the number of legs?

Out of Sync

Albert Einstein could see two clocks which were out of sync. For what fraction of the day did they show the same time?

Brothers and Sisters

Age 11 to 14 Short
Challenge Level


A boy has the same number of sisters as brothers.

Each of his sisters has only half as many sisters as brothers.

How many brothers and sisters are in the family altogether?




If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.


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