How do I find the odds or the probability of hitting a hard way parlay?

The house edge has nothing to do with the probability of hitting a parlay.

So it's a 1/11 chance to win. Multiply 1/11 times 1/11 and that's your chance of hitting a parlay, assuming by parlay you mean winning the hard 6 once, and then piling up all the money on the hard 6 to hit a 2nd time.

So to hit hard 6 (or 8) two times in a row as a parlay, you have a 1 out of 121 chance to pull it off.

For the hard 4 or 10, there is a 1/9 chance to win. 1/9 times 1/9 ends up being a 1 out of 81 chance to hit this as a parlay 2 times in a row.

Good news Aldo, theres a 100% chance thousands of asteroids hit the Earth every day. By the time they go in to the earths atmosphere they burn up in the mesosphere and become much smaller and eventually turn to ashes.There are big asteroids but be thankful those are hard to come by because if they ever did it could wipe out the entire nation.