The Excel PERMUT function returns the number of permutations (combinations where order is significant) of a given number of items. To use PERMUT, specify the total number of items and "number chosen", which represents the number of items in each combination.
Get total number of permutations
Total possible permutations as an integer
=PERMUT (number, number_chosen)
number - The total number of items.
number_chosen - The number of items in each combination.