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## 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!