A college student goes to the supermarket for groceries. By the end of his trip he's gotten fifteen items.
He goes up to the lane labeled "Express Checkout: 10 Items Or Less" and starts putting his purchases on the belt.
The cashier says, "Why, you must go to college at Harvard or MIT!"
"Why, yes I am a college student, but how could you know I went to Harvard or MIT?"
"Because Harvard students can't count, and MIT students can't read."