What if someone comes to the cashier and gives him the money he bought in the store? You have to change it for him. Choose to issue a second coin and give him / her the exact change. You choose all the appropriate coins to calculate the remaining coin changes. You can use coins of different sizes to repay the change, such as one coin or two five coins, depending on yourself. All you have to do is give him the right answer. Installation improves your application skills communication and becomes a "senior master" Install "approve coin calculation" and enjoy it.