Say you’re at a party with nine other people and everyone shakes everyone else’s hand exactly once. How many handshakes take place? This is the “handshake problem,” and it’s one of my favorites. As a ...

Historically, teachers have been criticized for verbalizing innovations while not acting on them. This study suggests that something more involved and complex may be happening as teachers move toward ...

To minimize brain strain when thinking recursively, start simply, look for a pattern and let the pattern do the work. Our April Insights puzzle explored the magical concept of recursion, a ...

Annals of Mathematics, a distinguished journal of research papers in pure mathematics, was founded in 1884. Annals of Mathematics is published bimonthly with the cooperation of Princeton University ...