- permutation: nPr = number of arrangements of “r” items taken from a set of
“n” distinct items (order matters!!)
= $\frac{{n!}}{{\left( {n - r} \right)!}}$

- combination: nCr = number of selections of “r” items taken from a set of
“n” distinct items (order does NOT matter!!)
= $\frac{{n!}}{{\left( {n - r} \right)!\;\;r!}}$

Permutation vs. Combination

Don't just watch, practice makes perfect.

We have 1274 practice questions in AU Maths Methods for you to work through.