Matthew from St Monica Junior School has sent in solutions to the first two parts of this problem:

You could be holding 3p, 6p or 7p.
31 matches, seeds, grains of salt or sand and safety pins would fit in a matchbox.

Natasha from Moorfield Juniors has answered the first part of this problem. She says:

I thought it would take longer to count in 10s to 300 because the numbers were longer.

A good point, Natasha. Do you agree?