I was struggling to understand the odds and outs section, so ive compiled my own calculations for probabilities:

Outs Turn River Both
1 2.13% 2.17% 4.30%
2 4.26% 4.35% 8.60%
3 6.38% 6.52% 12.90%
4 8.51% 8.70% 17.21%
5 10.64% 10.87% 21.51%
6 12.77% 13.04% 25.81%
7 14.89% 15.22% 30.11%
8 17.02% 17.39% 34.41%
9 19.15% 19.57% 38.71%
10 21.28% 21.74% 43.02%
11 23.40% 23.91% 47.32%
12 25.53% 26.09% 51.62%
13 27.66% 28.26% 55.92%
14 29.79% 30.43% 60.22%
15 31.91% 32.61% 64.52%

These are the correct probabilities in % for obtaining an out ('both' refers to getting an out in either turn or river).
I found a site ages ago that said to multiply your outs by 2 for 1 card, or 4 for 2. as you can see, this is somewhat accurate but not definative.
heres some equations:

Draw odds = Outs/Remaining cards x 100 (result x2 for 'both')
Pot Odds = Investment/Pot x 100

If Pot Odds is less than Draw Odds, play the hand

Hope this helps