From a strictly mathematical standpoint, you have debt on the house at 4.8%.

If we rope the expense in with rent and assuming 20% down you’ll see appreciation gain of 20% year one reducing to 4% at year 30.You should build a better mathematical model before your purchase but at slightly negative on cash flow, I am expecting returns of 13% over the first 8 years with an 8.5% interest rate on the mortgage.

For those who might be mathematically challenged, let's break this down...You just said that a professional tenant could live in your unit for 18-36 months before you can evict them and it could cost "easily...10 times" the $15K price of training. 

But they were just mathematical speculations on the success of mortgage bonds as a whole.

I have BS degrees in Computer Science and Mathematics and am currently a software engineer.

It is a very complex mathematical system that we investors need to be keenly aware of.

Every time I run the numbers I can not mathematically make financing work. 

This helps me sleep at night because I know #2 is the right mathematical decision, but having #1 also helps me with the psychological part of it.

There's this intricate mathematic relationship between interest rate,cap rate and IRRSo during QE era.

It may seem that it would make no mathematical difference whether it's deducted from one property or spread between the two of them, and often it does not.