Combinatorics: N choose K, permutations and subsets

[esraretin]

now i got it thank u

[esraretin]

i dont get it.now is this proof of coefficient of binomial theorem?

[mattgonzales89]

Really cool! I've always wondered the reasoning behind this. Understanding formulas always helped me recall it and now I'm sure to never forget what N choose K means or the formula. Thank you.

[fritzmh]

Best explanation ever! Iv'e been taught that thing in Spanish for many years and never understood why you do that procedure. Now I finally made it. Thank you!!!

[MathGeekQ]

thank you, just what i was looking for; a simple example illustrating what the notation n choose k means

[021radio]

thanks