The HP-12C is to mortgage people what the TI-83 is to algebra students.

People fail because they don't understand Geometry and Algebra.

The two most important books every REI must know, and understand (this is where many drop the ball), Geometry and Algebra.

I used basic Algebra...or whatever they teach you in elementary school. 

Do some algebra and that means: IRR = r = [(FV/PV)^(1/n)] - 1So obtaining the same total return (FV/PV) over a longer period (greater n) decreases the IRR exponentially.Doubling the investment in 4 years would be 18.9% IRR; 5 yrs, 14.9%; 6 yrs, 12.2%; etc.So other things being equal, the deal with higher IRR would be preferred, which usually means selling the property sooner rather than later. 

Now we do a little algebra ;-) Min: Income = 7% of Estate Value = 7% * Estate Value Max: Income = 3% of Estate Value = 3% * Estate Value Min: Value = Income / 7% = $12k / .07 = $171,400Max: Value = Income / 3% = $12k / .03 = $400,000So I would guess as much as $400 and as little as $170k. 

It is a measure of the effectiveness your purchase.We all know the metrics NOI, PurchasePrice and CapRate and the math is trivial to calculate (1) NOI / PurchasePrice = CapRate and simple algebra allows us to express other variations: (2) CapRate * PurchasePrice = NOI (3) NOI / CapRate = PurchasePriceMathematically, all three equations are correct - - however, only ONE is valid!

Here's what I would do:* Find Cash Partners* Find Credit Partners* Put together a Power Team* Write Down and organize your financial goals based on your financial needs (cash flow, personal debt)* Learn how to analyze markets to find the micro-markets that match your financial goals* Learn how money works (you will not learn this from most REI, or Harvard Business School)* Become highly proficient in both Geometry and Algebra (Analytical)* Understand the 2 Golden Rules of REI.* Understand the difference between:     * Good and Bad Debt     * Cost and Expense     * Cash Flow and Profit     * Good and Bad Equity ...at least that's where I would start...if I had to do it all over again.Which falls under the category of, "If I only knew then what I know now..."

The math part was not really bad in my opinion, its understanding how the algebra works.  

That being said, I use college algebra on a daily basis at work.