Firstly you might as well ignore the 3 because any multiple of 6 or 9 will be a multiple of 3. You're looking for a number between 61 and 107 that is in both the 6 and 9 times tables. Six: 60,66,72,78,84,90 (no need to go further than this, 90 is in the 9 times table.) Nine: 63,72,81,90. As you can see 72 and 90 appear in both and are appropriate answers.