Answer: 18
Step-by-step explanation: To find the least common denominator for 9 and 6, notice that 9 factors as 3 · 3 and 6 factors as 3 · 2.
When finding the least common denominator, we want to find factors that pair up and you can see we have a 3 that pairs up in our list.
Now we multiply our 3 that pairs up by the other 3 that doesn't match up and the 2 that doesn't match up so we have 3 · 3 · 2 or 9 · 2 or 18.
This means our least common denominator is 18.