Okay, but what if the Bank of Parents doesnt have the paper equivalent of the value of all of the coins?
If your child is older and has totaled all of the coins or has divided all of the coins and wants you to convert it to paper money now, tell the child that you will either (a) convert it to paper money a little at a time, or (b) take all the coins (with the child) to the bank to obtain paper money, or (c) allow the child to choose whether to spend (a.k.a. waste) approximately 8% of his money the fast and easy way by using a coin-converter machine usually found in supermarkets.
