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Question 1188946: Counting numbers are to be formed using only the digits 5, 4 and 2. Determine the number of different possibilities for two-digit numbers.
Answer by ikleyn(52921)   (Show Source):
You can put this solution on YOUR website! .
Placing any of three digits in the tens' position gives 3 opportunity,
and placing any of the two remaining digits in the ones' position gives 2 independent opportunities.
In all, there are 3*2 = 6 such tw0-digit numbers.
Solved and explained.
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The problem does not specify if the digits' repeating is allowed.
It is a HUGE HOLE in the problem's formulation.
My solution above is for the case, when repetition of digits is not allowed.
If, in opposite, it IS allowed, then the answer is different, OBVIOUSLY.
In that case, the answer is 3*3 = 9.
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