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 of a 2 by 2 matrix denominator "t" be zero. The formula above fails completely if "δ" and "τ" are both zero; that is, if "D" = −"A" and "A" = −"BC", so that both the trace and the determinant of the matrix are zero. In this case, if "M" is the null matrix (with "A" = "B" = "C" = "D" = 0), then the null matrix is also a square root of "M", as are for any real or complex values of "b" and "c". Otherwise "M" has no square root. If "M" is diagonal (that is, "B" = "C" = 0), one can