Square Root Day September 9, 1981 (9/9/81). Gordon remains the holiday's publicist, sending news releases to world media outlets. Gordon's daughter set up a Facebook group where people can share how they were celebrating the day. One suggested way of celebrating the holiday is by eating square radishes, or other root vegetables cut into shapes with square cross sections (thus creating a "square root"). Square Root Day occurs on the following dates each century: The number of years between consecutive Square Root Days in a century are consecutive odd numbers: 3, 5, 7, 9, 11, 13, 15, 17. This illustrates the fact that
Square root nonnegative. The term (or number) whose square root is being considered is known as the "radicand". The radicand is the number or expression underneath the radical sign, in this example 9. Every positive number "a" has two square roots: , which is positive, and −, which is negative. Together, these two roots are denoted as ± (see ± shorthand). Although the principal square root of a positive number is only one of its two square roots, the designation ""the" square root" is often used to refer to the "principal square root". For positive "a", the principal square root can also