Question 890639: how many 3 digit numbers can be formed using 0,1,2, and 3 if no 2 digits are the same?
the solution used was H T U = 3 x 3 x 2 = 18
i didn't get how hundreds, tens, and unit became 3 x 3 x 2. is there a way for me to easily understand?
thanks in advance.
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! For each of the  possible choices for the hundreds digit,
you have  choices for the tens digit,
making  choices for the first two digits.
Then for each of those choices,
you have  choices for the last digit,
for a total of
 choices.
You cannot use 0 as the first (hundreds) digit, because it would really make a two-digit number.
You have only 3 choices (1, 2, or 3) for the hundreds digit.
The number of possible choices for the hundreds is  .
For each of those choices, you have have eliminated one of the digits listed above,
but for the other digits you can also use 0.
As you have 3 digits not yet used that you can use for the tens and units digits,
the number of possible choices for the tens digit is  .
Each possible choice of hundreds and tens digits leaves you two digits not yet used,
so the number of possible choices for the units digit is  .
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