Binomial Coefficient

Binomial coefficients are numbers that tell you how many ways you can choose a certain number of items from a group without caring about the order. They're handy for counting possibilities in things like combinations and probability calculations.

{n \choose k} = \frac{n!}{k!(n-k)!}

More formulas

The Binomial coefficient is 1 when:

${n \choose n} = {n \choose 0} = 1$

more formulas

(x+y)^n = \sum{k=0}{n} {n \choose k } x^k y^{n-k}

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