@Joe VilleneuveHey Joe,I’m actually well trained in mathematics and actually won a state-wide math competition for high schoolers In South Dakota (not meaning to brag).

But mathematically, the money doesn't really exist.

Will it mathematically be better to own multiple properties with 30 years terms and pay much more interest or shorter terms with less properties?  

I would never suggest this to the average citizen but mathematically it can make sense. 1.

If 61,586 people moved to Austin in a single year then mathematically Austin would need an increase of 24,933 new construction homes/apartments to break even at 2.47 persons per home.  

But today, you have a considerable amount of equity built in paydown and appreciation to access, and you can use that equity to improve the current house and purchase more.Many people find suitable alternatives to manage a handful of properties from a distance, so even if you move eight hours away, you can do most of the managing yourself by building relationships with contractors and real estate agents, paying a small fee for them to help as need requires.Only sell if you know the choice is mathematically correct, rationally made, and leads to more property acquisition now.

Therefore, it is a very complicated mathematical model.

Mathematically it doesn't make sense to invest, however I am comfortable in this market and I know it very well.

In mathematics it is called "Proof Theory" It is a WHOLE field of mathematics one can get into... and yes I went into it.

If you think pure mathematically, the amount of tenants out there who are going to stay 5+ years and move during "normal" months is always going to be drastically lower than the folks who move ever 1-2 years and all months of the year.