Originally Posted by braveslice
Do you think we can use rule 2 and 4?
Here we would get 8*4 = 32%


That rule is made to have a quick approximation of the probability, so it's never exactly the same, but it's quite accurate.
For the x2 : You have 8/44 chance of hitting, which is 18.1% while the rule gives 16%, so it's pretty close.
Fort he x4 : The exact probability is around 33% and you get 32% with the rule, so it's again quite accurate.
And it's pretty much the same for every number of odds possible. I tried with a few different values and found that it always gives a bit smaller pourcentage, so it's a good thing cause it means you're a bit more cautious if you play around equity and EV.
I don't think the rule is based on math, instead it's probably based on an observation that it always gives a quite accurate results. So yeah, that rule works for Omaha too.