The square root of 81 is an integral number.
0.037
81 seconds on a stopwatch.
Area = pi*r*r = 81*pi => r^2 = 81 => r = 9 so d = 2*r = 18 ft.
if the question were 81 S in a S P the answer would be 81 Squares in a Sudoku Puzzle so the extra S letter is a mystery unless 81 Squares in a Standard Sudoku Puzzle as there are other variations
81 = square of nine
J. R. R. Tolkien died on September 2, 1973 at the age of 81.
81.1667
J. R. R. Tolkien died on September 2, 1973 at the age of 81.
Since 81 - 16r^2 is a multiple of both 4 + r and 4 - r, it is automatically the LCM of this problem.
81
27
"Eighty-one Squares in a Sudoku".