How many possibles solutions can a 9*9 sudoku grid have if it uses the numbers 1 to 9?

If you have every played a sudoku puzzle, you know that there are a lot of combinations of numbers. That is because of the fact that there are so many squares. Plus, there are nine numbers to fit into each square. The number of possible solutions for a regular nine by nine sudoku grid and it uses the numbers one through nine is six sextillion, six hundred seventy quintillion, nine hundred three quadrillion, seven hundred fifty-two trillion, twenty-one billion, seventy-two million, nine hundred thirty-six thousand, nine hundred sixty.

This is calculated based on the probability using both the number of squares on the board which is eighty-one and the number of numbers that are being used which is nine since numbers one through nine are used.