You dad gives you 10 dollars allowance a week. Your older brother is a bully and every week he punches you until you give him 10 percent of your allowance, which comes our to one dollar

You tell your dad you want to go to Disneyland this year so he tells you to save your money. He says he will hold on to it for you, so every week you give him 2 dollars. Now when your brother comes to punch you and get his 10 percent, he only gets 80 cents, because you only have 8 dollars left instead of the full ten. So you get to save money and the amount you owe your brother is less, because you are saving it before your brother takes his 10 percent.