factorials are mostly encountered in combinatorics, which is problems like, how many ways are there to put 3 objects of different colors in a row? well, the first can be any of the 3, the second can be either of the other 2, and the last is whichever 1 is left, so 3×2×1=3!=6
so how many ways are there to put 0 objects in a row? well there’s 1, it’s this one:
And the other half is 0! 5 0
0! is 0.
Edit. I remembered wrong. Keeping it like this as it is funnier that way.
Man math is hard
I love this so much
factorials are mostly encountered in combinatorics, which is problems like, how many ways are there to put 3 objects of different colors in a row? well, the first can be any of the 3, the second can be either of the other 2, and the last is whichever 1 is left, so 3×2×1=3!=6
so how many ways are there to put 0 objects in a row? well there’s 1, it’s this one:
that’s why 0!=1
Wow, that was a really great explanation! Thanks! I could have needed this twenty years ago and maybe we wouldn’t have had this interaction.