My favorite proof of the n choose k formula!

The binomial coefficient shows up in a lot of places, so the formula for n choose k is very important. In this video we give a cool combinatorial explanation of that formula!

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Music: OcularNebula - The Lopez

[Mrcloc]

You're a good teacher. You repeat things without sounding like you're repeating them. Gives time for things to sink in and gives a few ways to think about it.

[azzeddinebekkari]

I am a mathematics Ph.D. student, and I use this formula all the time I never thought of its proof, I really found this proof elegant and well explained. Thanks.

[vanishmanesh]

Really elegant and clearly communicated. You're underrated. Thanks

[reshmabhagwat]

Very good, but need to watch this again and again to grasp it completely. Generalizations are always more difficult to prove than specific cases. Thank you.

[ianyu]

ACT student here. had a question that needed this equaiton for a question. Explanation really made it clear how this works. Thanks

[dr.mikelitoris]

Sorry babe you’ll have to wait mu prime math just uploaded

[jorgeuliarte]

Very good, as ever. Thanks for your efforts to bring this science to everybody. From Salzburg, Jorge

[frankyin]

bravo 👏🏻 i’ll never forget the induction of that formula

[chandansinghdhami]

I am learning from nepal. I love the way you teach.

[DirtyHuman]

Lovely proof.

This video can be enjoyed by any level of student.

[farrukhazfar]

Best proof of this I've ever seen - I wish you had been my high school teacher

[tny]

Amazing proof! Very easily digestible, great content

[mrigayu]

Love the t-shirt! And that is indeed a great proof

[tomkerruish]

Nicely done! Still waiting for you to start lecturing from 201 Bridge or 22 Gates.😁

[eldestisland]

This was extremely clever! Thanks for the explanation 👍

[deathstorm]

this feels like factor groups in abstract algebra, each subset of permutations feel like a coset. but what is the normal subgroup? or is this just completely different?

[jfcrow]

k! is order mattering -> (n-k)! is order mattering. -> n! is number of orderings with ordering mattering -> n choose k is ordering not mattering Whattt?

[fromhua]

why do we have to multiply n choose k at the end to make n!😢😢

[Couldyanot]

What a perfect explanation, well presented as well

[MrsBostic-hi]

Clearly stated.
luved it!
Bravo'