Thanks for the query.

The series is progressing as a multiple of 3 => (1/9), (1/9)*3, (1/9)*3*3,........

That is, the next number is a multiple of 3 of the previous one.

**Hence, the sequence should be (1/9), (1/3), 1, 3, 9, 27,........**

Hence, the required number is 3