Bill is a good and intelligent student who enjoys arithmetic and can easily solve all the problems in his textbook.
One day on his way to school, Bill passed a fruit store. A sign in the window read: "Apples—Six for five cents." An idea struck him, and he went inside.
"How much are the apples?" he asked the shopkeeper.
"Six for five cents."
"But I don't want six apples."
"How many do you want?"
"It's not about how many I want. It's an arithmetic problem."
"What do you mean?" asked the man.
"Well, if six apples are worth five cents, then five apples are worth four cents, four apples are worth three cents, three apples are worth two cents, two apples are worth one cent, and one apple is worth nothing. I only want one apple. If it's worth nothing, I don't need to pay you."
Bill picked out a good apple, began eating it, and walked happily out of the store. The man looked at the boy in such surprise that he couldn't say a word.