Repetition not allowed: For a number to be a 3 digit number, 1st digit should be from 1 to 9, excluding 6 which is at the 3rd digit's place. For 2nd digit, there are only 8 choices after including 0 and excluding the digit taken as the 1st digit and 6 at the 3rd digit's place. For 3rd digit, only 1 choice is there which is 6. So total 3 digit numbers that can be formed which end with digit 6 = 8x8x1=64