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 Cardano's "Ars Magna". According to historian of mathematics D.E. Smith, Aryabhata's method for finding the square root was first introduced in Europe by Cataneo in 1546. According to Jeffrey A. Oaks, Arabs used the letter "jīm/ĝīm" (), the first letter of the word “” (variously transliterated as "jaḏr", "jiḏr", "ǧaḏr" or "ǧiḏr", “root”), placed in its initial form () over a number to indicate its square root. The letter "jīm" resembles the present square root shape. Its usage goes as far as the end of the twelfth century in the works of the Moroccan mathematician Ibn al-Yasamin. The symbol '√'