Specifically:value = rent / 0.01 (estimated via the 1% rule)NOI = 12 * rent * 0.5 (estimated via the 50% rule)cap rate = NOI / value = (12 * rent * 0.5) / (rent / 0.01) = 12 * 0.5 / (1 / 0.01) = 6 * 0.01 = 0.06In other words, combining the 1% rule and the 50% rule is the mathematically the same as assuming a 6% cap rate for residential.

My advise would be to focus on analysing a business thoroughly and not quickly before making an investment decision.Naturally there specifics to different industries which one needs to know to evaluate the quality of a revenue stream; the reasonableness of operating expenses; and whether the debt load being carried is appropriate, but the mathematical callisthenics are the same.Screening a property, or business, to see whether it warrants further examination is a different matter.  

Like I said, I am new, no properties YET, but trying to get a feel for my local market and working on the mathematical formula to start to recognize how the numbers "move" in order to recognize deals.

sometimes its just nice to own a trophy property which basically describes the better areas of SD.of course you can refi till you die and use all those mathematics that of course on paper make sense.but what if U sell it try to buy in a market that gives you a little more return on paper ( which is generally low B to C class) and now your stuck in an asset that's tough to manage and can go without rent fairly often because the tenants are NOT SD tenants .   

Mathematically if you can make a greater return than that 3% then you should pay the minimum on the loans and invest the extra cash, which will enable you to keep the difference between the interest on your investments and the interest on the loans.

I have a certain threshold depending on return but it is not a mathematical formula, just a feeling based on my knowledge and experience, which of cause is constantly changing and hence the "risk factor information" is constantly being reevaluated.How do you account for risk in your evaluation of potential investments?

The answer to this question lies in the mathematics.

However, I majored in mathematics, and I have no interest in pursuing a career in mathematics as I found myself to not understand it or like it very well (not yay).

I've been messing around in Excel trying to find a formula or mathematical adjustment to get close to the adjustments the appraisers made (each appraisal from a different appraiser) for Gross Building/Living Area Square Footage.The whole point of all this is to get a pretty accurate ARV.

I have no interest in paying off my student loans early for the same mathematical reasons that many others have already mentioned.