So if you multiply your 4-month return by three, you will get your ROR, which is the real number to keep your eye on, since that allows you to normalize returns across other options.  

Understanding what area that you are referring to, the multipliers there favor a different price point, unless you can get it to retail condition.

I can take that money and multiply it with other investments.

Advertising is salesmanship multiplied by reaching more people via targeted direct mail, or other media whether online or offline. 

What you calculated was the gross rent multiplier which has nothing to do with CAP. 

Multiply X with your median carpet price.

Math you can break down into multiple parts.For real estate if you have a grasp of addition, subtraction, multiplying, division etc. then a lot of calculations should be able to be made.If by saying you are not good in math you mean calculus, trigonometry, and algebra etc. that stuff is more used in other occupations like a scientist etc.

I'm assuming it wouldn't work to just multiply the per room rate by three. 

Ask for his schedule c to see what he's reported to the government and call the utility companies yourself to see if they will give you an average cost monthly then multiply that by 12 for your annual costs.  

Multiply this simple deal by thousands, and the total bank assets is reduced considerably and the health of bank doesn't look as good and may not pass the test by Feds.Just my thoughts.Rich