Let's start with a bigger number first and it will become clear.
952406 => not a multiple of three
95240 => not a multiple of three
9524 => not a multiple of three
952 => not a multiple of three
95 => not a multiple of three
9 => Bingo! return 9

36 => Bingo! Remove nothing, return 36

Return n if the input is already a multiple of three

last number starts from the right (units' place, then tens', then hundreds' ...)

nope, you still need to do import kotlin.math.pow

I think the method 'pow' belongs to the Math class. It's static so you invoke it like this 'Math.pow(someInt,someOtherInt)'
And it needs two parameters, no?
The Math class lives in java.lang so you don't need to import it.
Apologies if you're thinking of a different pow method.

You have to import it before you can use it.