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Evaluate binomial coefficients

curriculum/challenges/english/blocks/rosetta-code-challenges/598de241872ef8353c58a7a2.md

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--description--

Write a function to calculate the binomial coefficient for the given value of n and k.

This formula is recommended:

$\binom{n}{k} = \frac{n!}{(n-k)!k!} = \frac{n(n-1)(n-2)\ldots(n-k+1)}{k(k-1)(k-2)\ldots 1}$

--hints--

binom should be a function.

js
assert(typeof binom === 'function');

binom(5,3) should return 10.

js
assert.equal(binom(5, 3), 10);

binom(7,2) should return 21.

js
assert.equal(binom(7, 2), 21);

binom(10,4) should return 210.

js
assert.equal(binom(10, 4), 210);

binom(6,1) should return 6.

js
assert.equal(binom(6, 1), 6);

binom(12,8) should return 495.

js
assert.equal(binom(12, 8), 495);

--seed--

--seed-contents--

js
function binom(n, k) {

}

--solutions--

js
function binom(n, k) {
  let coeff = 1;
  for (let i = n - k + 1; i <= n; i++) coeff *= i;
  for (let i = 1; i <= k; i++) coeff /= i;
  return coeff;
}