Art of Problem Solving: Counting Objects in a Circle Part 2

Art of Problem Solving's Richard Rusczyk explores counting the number of ways to arrange objects around a circle when the circle can be flipped over.

[alexander_liu_]

0:55 lol "warning to other keys".

[MagicPrezident]

How can I e-mail you Richard if I think know what the silver mystery key is for?

[hansenhe]

I'm wondering how his hands aren't sticky...

[cavetivitic]

"I have more!" Pulls out 10 keys😳

[jnxmaster]

At 2:22 you say:
"Now _n!_ is just _(n*n-1)!_, so we can cancel out the n's there..."

Why is _n! = (n*n-1)!_ ? Can someone explain.

[samarahassranah]

Do you know how I can find the no of arrangements in. A circle, I the objects are repeated?

[unimiaw]

i just keep repetedly watch 12:34 of the video