How many levels are there in the super mario bros. game & watch game?

I've had a super mario bros. game and watch for probably a year now and i've never sat down to get through as much of it as possible. i was simply wondering if it was an on-going game like an arcade game, or if there were a set number of levels and it was possible to reach the end.

Google or YouTube would probably answer that.

7 worlds
4 levels in each world, iirc

not counting the negative world

so.. you do the math? :3 (28)