Who can tell the output before running the code

Question

This is a simple anonymous ruby code.
It's hard to guess before running but with a close inspection, I think you'll get it.
https://code.sololearn.com/cj0XpN0wr3Ld/?ref=app

Answer 1

Is it 27000?

_ is 0
__ is 1
___ is 3
____ is 27

Answer 2

Nomeh could you explain me about that kind of code by email? God bless you