The online computer game “Is this prime?” tests a player’s knowledge of prime numbers—and just surpassed 2,999,999 attempts. Give it a whirl. The Greek mathematician Euclid may very well have proved, ...

Peruvian mathematician Harald Helfgott gained worldwide attention in 2013 when he solved a 271-year-old problem: the so-called Goldbach’s weak conjecture, according to which every odd number greater ...