This is a fun one:

- Measure the rear spacing. If it's 120mm, you've got its original function: single speed, 3 speed, or fixed gear. Some might argue 5 speed from the 70's, but not with that seat collar and filet brazing going on.
- If it's >120mm, then we're into a geared frame. No braze ons for downtube shifters (but could have been clamp-on or stem shifters), no cable guides on the frame, and stamped dropouts (I'm sorry but the welds on those pancake dropouts do not indicate quality). If it was a geared bike, though, the rear brake bridge would have to be drilled. If it's not a geared bike--then none of those brazed on cable guide matter.
- Obviously the front fork is off another bike.
- The cup+cone bottom bracket indicates low quality (assuming this bike is post-2000).

Either the bike was a track frame to begin with (unlikely because of the horizontal dropouts), or it was a 3 speed/coaster brake bike. Flick the tubing of the main triangle with your fingernail to test for double-butting. If it doesn't change tones closer to the welds, it's either straight gauge chromoly or basic no-name gaspipe.

But, $10 to find out--probably worth it.