# MDM4U Combinations 2016-02-16

I gave a short quiz on permutations, then we started into combinations today.

The number of combinations of $r$ distinct items chosen from $n$ distinct items is

$_nC_r = \binom{n}{r} = \frac{n!}{(n-r)!r!}$

We say “$n$ choose $r$“.

We’re going to practise a bunch tomorrow.

For tonight, complete Page 279 # 1, 2, and 4, and finish your Permutations Review. Thanks :)