The next number in the series is 729.
This series is made up of powers of 3. We can observe the following:
- 3 is 31
- 9 is 32
- 27 is 33
- 81 is 34
- 243 is 35
As we can see, each number is obtained by multiplying the previous number by 3. Therefore, the next number in the series can be calculated as:
243 × 3 = 729
Thus, the next number is 729.