# Square Root Day

Geeks unite—we have another math holiday to celebrate!

April 4, 2016 is one of the rare Square Root Days in the mathematical world. April is the fourth month of the year, and 4 x 4 = 16. Why is it called Square Root Day? Four is the square root of sixteen:

These ideal days occur only nine times in each century. There is one in every year where the last two digits of the year are a perfect square—such as 16!

There won’t be another Square Root Day until 2025, so pull out your calculator while it lasts and give it your undivided attention. First promoted by Rob Gordon on September 9, 1981, it’s a perfect day to go square dancing, eat root vegetables, and count perfect squares.

The symbol for the square root is the radical sign, or radix. Radix is Latin for “root”. This symbol was introduced by the German mathematician, Christoph Rudolff, all the way back in 1525—a year with a Square Root Day! The symbol may have been derived from the Latin letter R, but no one knows for sure.

Happy Square Root Day!