Both bathroom decorators and mathematicians have a reason to rejoice (how often does that happen?). Using a computer algorithm, a group of mathematicians at the University of Washington Bothell discovered the 15th kind of pentagon that can tile in a plane. The 14th was discovered in 1985 by mathematician Rolf Stein, while the previous five before were proven by Majorie Rice, a housewife from San Diego.

**Mathematics, News**