Factorial/Examples/1,000,000

Example of Factorial
The factorial of $1\,000\,000$ has $5 \, 569 \, 709$ digits.

Proof
Let $d$ be the number of digits in $1\,000\,000!$

From Number of Digits in Factorial:
 * $d = 1 + \left\lfloor{\left({n + \dfrac 1 2}\right) \log_{10} n - 0.43429 \ 4481 \, n + 0.39908 \ 9934}\right\rfloor$

from which the result can be calculated by setting $n = 1\,000\,000$.