This activity is designed to be accessible to primary school pupils at Key Stage 2.
Detailed teachers' notes for this activity are available on our NRICH website.
Further information
If you're finding hard to get started, try looking at this hint.
Detailed teachers' notes for this activity are available on our NRICH website, where you can also find thousands more mathematical resources including problems, investigations and games for all ages from 5 to 19.
