Why 0! = 1 ? The 10-Second Explanation #mathtricks #maths #shorts

Added: 2026-05-23

[00:00:00]Is zero factorial [music] actually equal to one?

[00:00:02]It sounds crazy, but here's why. In math, a factorial counts the number of ways you can arrange a group of items.

[00:00:06]For example, [music] if you have three books, there are exactly six ways to arrange them on a shelf: ABC, ACB, BCA, BAC, [music] CAB, and CBA.

[00:00:15]That's why three factorial equals six.

[00:00:16]So, what about zero factorial? Following that logic, >> [music] >> zero factorial asks, "How many ways can you arrange zero books?" Well, there's exactly one way to do it. You leave the shelf completely empty.

[00:00:25]You have [music] one empty set, and that is why zero factorial equals one.