1. The problem statement, all variables and given/known data How many 3 digit numbers can be formed from 0 to 3 without repition 2. Relevant equations 3. The attempt at a solution What I did first is H = number of choices for the hundreds place T = number of choices for the tens place U = number of choices for the units digit H = 3 possible choices (excluding zero) T = 3 possible choices ( including zero but excluding whatever is in the hundreds place) U = 2 possibe choises (including zero but excluding whatever are in the hundreds place tens place) Therefore 3x3x2 = 18 numbers can be formed But I noticed something. When do the selection in reverese that is selecting the choices for units digit first then the tens place then hundreds place I get a different answer U = number of choices for the units digit T = number of choices for the tens place H = number of choices for the hundreds place U = 4 T= 3 H = 1 Therefore 4x3x1 = 12 numbers Can you guys explain why this happens? Thanks!