Chester broke the cover to his calculator. So I made him a new one.
Here it is:
The abacus is on the back, so that the flap doesn't interfere. It's a Chinese abacus, because that's the same kind that my kids have for their homeschooling. Chinese kids still learn their beginning math this way. The five on the bottom are 1, 2, 3, 4 and 5. Then six is 1 on the bottom and 1 on the top. 2 on the top is 10, and carries over to the next column left.
It's a felted sweater (of course), sewed into a bag with a flap.