1.) Let's say we are given 2 digits not equal to each other...The number of different orderings would be 2*1 = 2, or if we wanted the number of ways to order 2 digits chosen : 10*9 = 90 ways
2.) The number of ways to arrange 3 letters from 26 letters is:
26 Permutes 3 = 26! / (26 -3)! = 26*25*24 = 15,600 ways to choose 3 letters in a certain order
3.) 4 different chores. The number of ways to do them = 4*3*2 *1 = 24 ways