A professor handed out the test to his students and returned to his desk to wait. When the test was over, the students filed over and handed in their papers.

As the professor was going through the submissions, he noticed one student had taped a hundred dollar bill to his test. On the bill the student had written ‘A buck a point’.

The next day the professor handed back the tests.

The student who had attached the hundred also received an envelope containing sixty-four dollars. On it was written ‘Here’s your change’.