A dance instructor chose four of his 10 students to be on stage for a performance. If order does not matter, in how many different ways can the instructor choose the four students? 210 1,260 6,300 25,200

This is a combination in which you choose 4 from 10.

The formula is

combinations = 10! / 4! * (10-4) !

combinations = 10! / 4! * 6!

combinations = 10 * 9 * 8 * 7 * 6! / 4! * 6!

combinations = 10 * 9 * 8 * 7 / 4 * 3 * 2

combinations = 10 * 3 * 7

combinations = 210