1/9, 5/81, 17/27
9 = 3 * 3
81 = 3 * 3 * 3 * 3
27 = 3 * 3 * 3
It's like we're making a list of parts that we can use to make either of these numbers (9, 81, 27).
Our parts list is 3 * 3 * 3 * 3 because that list contains enough parts to make either 9, 81, or 27.
3 * 3 * 3 * 3 = 81
Answer: The least common denominator (LCD) is 81.