How many different 6- player starting squads can be formed from a volleyball team of 11 players?

You have to calculate how many combinations of 6 people can be chosen from 11.   The formula for this is:
n! / [r! * (n-r)!]
combinations = 11! / [6! * 5!] =
11 * 10 * 9 * 8 * 7 /  5 * 4 * 3 * 2 *1 =
11 * 3 * 2 * 7 =
462 Combinations

Source:
http://www.1728.org/combinat.htm