AMHERST, Mass. — A Massachusetts college has changed all the speed limit signs on campus to honor a retired mathematics professor who spent his career fascinated by the number 17.

The speed limit change from 15 mph to 17 mph at Hampshire College was made at the request of the professor, David Kelly. He didn’t want a retirement party when he stepped down after 45 years on the faculty at the college in Amherst.

Kelly knows countless facts about 17, the seventh prime number. He said it has had broad applications in mathematics and other disciplines. There are many fun facts about 17, including that there are 17 columns on the long side of the Parthenon in Greece.

Kelly said the tribute “captures Hampshire’s uniqueness.”