It puts the “!” in probability.
Sometimes it’s good to remember what a factorial is.
In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n.
10! = 10x9x8x7x6x5x4x3x2x1x = 3,628,800
Factorials show up in a lot of different places especially combinatorials and permutations.
They matter for us in arranging things in a sequence, like the ciphertext letters when trying to break a transposition…
For n letters there are n! ways of arranging them in sequence. The various ways they are arranged are the permutations.
There’s quite a bit more involved math with factorials but for now this is enough for me.