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How many 3 digit all even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 if the digits can be repeated?
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In the units position, only even digits 2, 4, 6 can be placed,
giving three different possible options.
In the tens and hundreds positions all of 6 given digits can be placed, independently,
giving 6*6 = 36 possible options.
In all, 6*6*3 = 36*3 = 108 different three-digit numbers are possible, having the assigned form.
Another way to solve is to notice that, in all, 6*6*6 = 216 three-digits numbers are possible,
and precisely half of them are even numbers.
It leads us to the same answer = 108.
Solved in two different ways, for your better understanding.