For the digit to be even, we must have 2,4,6 at units place.
So only 3 numbers are possible at units place.
The tens and hundreds place can be taken by any of the six numbers.
So total numbers will be =3X6X6
=108
Final Answer
We can form 108 3- digit even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 if the digits can be repeated.