Answer: Step-by-step explanation: 243
Lets look at the difference between the first two numbers (3 and 9). to get from 3 to 9, we either have to multiply by 3, or add 6.
Next, let's look at the difference between 9 and 27. to get from 9 to 27, you have to multilpy by 3, or add 18.
If we conitnue to multiply the previous by 3, we get the following number, therefore we know the answer is to multiply by 3.
if we multiply 81 by 3, we get 243