Solution

36767

First name
Joe sell
School
St John Fisher RC Primary, oxford
Country
Age
8

8 for the first box, 11 for the second box

We worked out the second box by seeing if eleven fitted in to all of them and then seeing if any multiples of 11 fitted in. They didn't so I think it is eleven.

With the first box I tried all the multiples that fitted in to 24, and the largest that fitted in to the other numbers was 8