One day a professor was giving a big test to his students.
He handed out all of the tests and went back to his desk to
wait. Once the test was over, the students all handed the
tests back in.

The professor noticed that one of the students had attached
a $100 bill to his test with a note that said, "A dollar per
point."

The next class the professor handed back the tests.

The student received his test and $64 change.