RAY: A landscaper returns from work and is sitting at the kitchen table with his kids. The kids ask, "Did you work hard today, Daddy?"

Dad says, "I did. I planted five rows of four trees each." His little third-grader, wanting to show off her newfound skills with the multiplication tables, says, "You planted 20 trees, Daddy!"

He says, "No, I'm sorry, you little twerp. That's wrong. I planted 10 trees." She responds, "That's impossible!"

The dad responds, "No, it isn't, and here's a hint: If you look at one of the math or history test papers that your teacher has returned to you recently, you're going to find the answer."

The little girl sits there and thinks for a minute, and then she says, "I've got it!"

What did she find on her paper that gave her the answer?

[ Car Talk Puzzler ]