Pronunciation of Combinatorial Functions

Question

A quite unimportant, but still systematically necessary question is how you go about pronouncing some of the basic combinatorial functions. Namely, the combination and permutation function. How do you properly pronounce $nCr$ and $nPr$?

Answer 1

As others have noted, the binomial coefficient $nCr = \binom{n}{r}$ is pronounced "$n$ choose $r$."

The "falling factorial" $nPr = (n)_r = r!\binom{n}{r}$ can be pronounced "$n$ to the $r$ falling.": https://en.wikipedia.org/wiki/Falling_and_rising_factorials#Alternative_notations