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!