Factorial/Examples/1,000,000
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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:
- $d = 1 + \floor {\paren {n + \dfrac 1 2} \log_{10} n - 0.43429 \ 4481 \, n + 0.39908 \ 9934}$
from which the result can be calculated by setting $n = 1 \, 000 \, 000$.
$\blacksquare$
Historical Note
The factorial of $1\,000\,000$ was calculated in its entirety by Harry Lewis Nelson and David Slowinski.
The computer printout was $5$ inches high.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $24$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $24$