And this year, the fifth of May is filled with mathematical joy. It is — Square Root Day! It all started in 1981. "I was writing a check in late August," says Ron Gordon, who originated bringing ...

The date so written - 4/4/16 - represents just one of nine so-called Square Root Days every century. The last was celebrated on March 3 2009 and the next one will be marked on May 5 2025.