Maybe we could have a Part II: Math to know post-flop.
Such as: You have 7
7
on a flop of 6
2
2
You bet & it folds to your aggro LAG who shoves. You deduce that he wouldn't shove with an over-pair here, because he doesn't have a big PP because he didn't 3! pre. So, you put him on two A2s, that he may shove with trying to get you to think he's weak [with a FD] & a flush draw with two overs, or a FD with A3s-A5s.
There are 2 A2s & 3 AXs that he would do it with: A9s & A8s & A7s & A5s. He is aggro enough to 3! pre with AJs+.
You have ~9% equity vs. the two A2s & ~54% equity vs. the four FDs, or 2:1
So, [9+54+54]/3 = 59% equity vs. his range.
If we're only putting in something like 35% of the money, if we call, we have a substantial overlay that can compensate for a reduced number of of FDs he may hold.
For instance, if he only has 2 FDs, it would 1:1 & [9+54]/2 = 32%, so we would need him having 2 FDs in the [A3s-A5s range] where he only has 1 overcard for [9+59+59]/3 = 42% equity.
So what we need to have memorized:
1. An overpair vs trips has 9% equity.
2. An overpair vs a flush draw with 2 overs has 51% equity.
2. An overpair vs a flush draw, 1 over & runner/runner str8 [under our PP] has 59% equity.