(from http://www.halfbakery.com/idea/Inverse_2...0_27_3f_27)
Quote:Inverse Factorial '?'
The inverse of the factorial operation should be '?'
It seems logical that the inverse of the factorial function, '!', should be '?'.
Then you would have meaningful identities like:
9! = 362880
362880? = 9
9?! = 9
362880?!?!?? = 9
3! = 6 = 720?
1! = 1? = 1?!??!?!!?
It would really clear up mathematics, especially for the novice.
—
AntiQuark, Oct 27 2004
Gottfried Helms, Kassel