Factorial/Examples/21

Example of Factorial

$21! = 51 \, 090 \, 942 \, 171 \, 709 \, 440 \, 000$

Proof

From $20$ Factorial:

$20! = 2 \, 432 \, 902 \, 008 \, 176 \, 640 \, 000$

Then:

  2 432 902 008 176 640 000
x                        21
---------------------------
  2 432 902 008 176 640 000
 48 658 040 163 532 800 000
---------------------------
 51 090 942 171 709 440 000   

$\blacksquare$