The least common denominator of 1/6 and 7/9 is 18. Why? Well, we can start by listing the multiples of both denominators (the numbers on the bottom of the fractions) which are 6 and 9.
Multiples of 6:
6, 12, 18, 24, 30, 36, 42, 48, 54, 60
Multiples of 9:
9, 18, 27, 36, 45, 54, 63, 72, 81, 90
By identifying the multiples of these numbers, we can see that the lowest multiple these integers have in common is 18. Because of this, the least common denominator of 1/6 and 7/9 is 18.
Your final answer: 18.