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Place this "worm" on the 100 square and find the total of the four squares it covers. Keeping its head in the same place, what other totals can you make?

Book Codes

Age 7 to 11 Challenge Level:

Why do this problem?

This problem could intrigue some children. It gives plenty of practice in multiplication and addition.

Key questions

When was the book published?
Do the numbers have any factors in common?
Do you know how to check that a number is divisible by 2, 3, 4, 5 ...?

Possible extension

Some children could research the properties of more recent ISBNs.

Possible support

Using a calculator will free up some children for thinking!