# What operation is denoted by this subscript notation?

What operation is denoted here?

$$11_3$$

I believe the answer to this is 4.

$11_3$ is the number $4$ written in base $3$: $$11_3 = 1\cdot 3^1+1\cdot 3^0 = 3+1=4$$ A small nitpick: it is not technically an operation, but a notation.
$11_3=4_{10}$.