No 1-digit number can contain two 6's. There is only one two digit number that contains exactly 2 6's. That is the number 66. The three-digit numbers are of the form _66, 6_6, or 66_ 1. _66, there are 8 ways to fill the blank, as we cannot fill it with 0 or 6. 2. 6_6, there are 9 ways to fill the blank, as we cannot fill it with 6. 3. 66_, there are 9 ways to fill the blank, as we cannot fill it with 6. A total of 8+9+9 = 26 three-digit numbers. that's 1 two digit number plus 26 three digit numbers = Answer: 27. Edwin