The number of combinations can be calculated by:
C = n! / r!(n - r)!
where n is the number of things to choose, and we choose r of them without repetition, and order does not matter, because in multiplication ab = ba.
The symbol ! is the factorial function, and it means 1x2x3x4x ... x n.
However, in this situation, the value of r will vary from 2 to 5. Therefore, it will be necessary to calculate C for each value of r, and then add the results.
I hope this information will put you on the right track.
