WOLFRAM|DEMONSTRATIONS PROJECT

Factorial Digits

​
millions
1
thousands
1
ones
1
number of leading digits
5
1001001! =
13643…8
250247
︷
000…000
︸
5571716
Computing
n!
leads to large numbers quickly. In fact, the largest factorial most calculators can handle is 69!, because 70! is a 101-digit number. It is easy, however, to compute a few leading digits and the total number of digits, as well as the number of trailing zeros of a factorial. With some extra work you can also compute the last nonzero digit.