As a high school student in the mid-1990s, Pace Nielsen encountered a mathematical question that he’s still struggling with to this day. But he doesn’t feel bad: The problem that captivated him, ...

Earlier this year, a trio of mathematicians decided to make lemons into lemonade — and ended up making major headway on a problem that mathematicians have been thinking about for centuries.

One idle evening last October, Mehtaab Sawhney took up an old pastime. He began perusing the website erdosproblems.com, an updated record of the 1,179 conjectures left behind by the eccentric and ...