Brian Butterworth is on a crusade to understand the number deficit called dyscalculia — and to help those who have it. In the mid-1980s, Paul Moorcraft, then a war correspondent, journeyed with a film ...

About a year ago, the theoretical chemist Salvatore Torquato met with the number theorist Matthew de Courcy-Ireland to explain that he had done something highly unorthodox with prime numbers, those ...