Question

How many combinations are there of the five letters j, k, l, m, and n using four letters at a time

Answer 1

\[nCr = \frac{n!}{(n - r)!r!}\]\[5C4 = \frac{5!}{(5 - 4)!4!}\]

Answer 2

\[5C4 = \space?\]

Answer 3

whattttt

Answer 4

Have you learned about factorial?