## Permutations and Combinations

The permutation of n things taken r at a time, nPr,
is calculated as follows. For _{5}P_{3} enter
5
and press three times to select PRB.
Then, select nPr by pressing . Enter the value of r,
which is 3 and press .

The combination of n things taken r at a time, nCr,
is calculated as follows. For _{6}C_{4} enter
6
and press three times to select PRB.
Then, select nCr by pressing . Enter the value of r,
which is 4 and press .