Mathematically, for Leia, Luke, Han, and Chewie to escape a giant station with a crew+army of 1 Million and inferior weapons, solve for probability?

There are a couple of things here -
One - the Empire let them escape so they could track them to the rebel base, so chance of escape was 100%, according the Empire's plan.
Two - not everyone on board the station is combat trained, so most of the people on board are support personnel, workers, officers, and people who aren't trained to fight, so the number of active soldiers they'd have to fight through is way less than the total people on board.

Now, assuming that they actually did not want them to escape, then they would have put up more of a fight, both in the corridors, and in space. They only launched like three fighters to follow them. If they wanted them dead, the Death Star had whole squadrons at their disposal. I'd put it at near 0% chance of escape with that factored in.


But that's all just speculation - I don't know how one would make an equation to fully calculate it.

Leia theorized (which was confirmed by Vader) that the storm-troopers [i]let[/i] them escape. A tracking device had been hidden on the Falcon and Vader intended to us it to follow them to the rebel base. Of course, this was in the context of a movie where a ship as small of the Falcon somehow has gravity inside it and can travel the length of the galaxy in a matter of hours at the speed of light (it would really take 100,000 years at that speed).

...you need to get out more.

The Force