Punch by Numbers at the Gym

I have no idea how to use this machine, but I sure feel better after punching it.

I know there must be a method to using this piece of work-out equipment, but for me, I just start punching away. Maybe I look like a weirdo, but hey, after I punch the numbers for 5-10 minutes, I start working up a sweat and I get all my frustrations out of my system!

If you happen to know the correct way to 'punch by numbers,' please let me know. Until then, I'll just randomly punch the crap out of it.