- #1
paulmdrdo
- 89
- 2
Homework Statement
How many 3 digit numbers can be formed from 0 to 3 without repition
Homework Equations
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!