Ok, this is a bit lenghty, but stay with me. It may seem like a better question for the probability forum, but my question is more specific to SNGs

I'm reading Harrington's 1st book on tournament hold'em and am currently on the section concerning pot odds.

He takes you through his process of calculating odds by doing something like the following:

"I think his calling range is here is AK-A9, KQ-K10, and pocket 8's on up. I have pocket 9's.

There are 8 different unpaired hands he might call with. There are 16 ways to make each hand. 16x8=128. Of these 128 hands I will win about 75.

He will also call with pocket pairs 8 on up. There are 7 of these. They can be made with 6 combinations. 7x6=42. Of these 42 hands I will win about 9.

So out of 170 hands, I can expect to win 84 if called on this blind steal. I also have some fold equity here so blah blah blah blah..."

You get the idea.

Now, I love how Harrington reasons all this out, and I GET what he's saying. The problem is, I'm not a math guy. I can't calculate this stuff in 10 seconds. It would take me at least 30 seconds, probably more.

How do I apply this to online SNGs where you only have 20 seconds to make a decision? Do I keep a chart nearby and memorize it? Do I give myself practice hands at home and do the math hoping that I get quicker at it?

I know the top SNG players must be doing something very similar to Harrington as they're playing. Any tips on a quick system of calculating my odds?