It is a mathematical certainty.It has been extremely difficult to have not made money investing in San Diego RE as my two poorly timed examples demonstrate. 

The 30k was just "invested" at a fixed rate return of whatever the mortgage rate it paid off was at.Now how everything ties in with the move and getting situated at the new job and all that, that takes it away from a pure mathematical/leverage situation, and is also very personal.

I hire a college graduate in mathematics, who has a sense of humor, can pass rigorous background check, has perfect credit, and has desire to learn sales. 2. no mortgage company gives free leads3. mortgage loan officers do not get salaried, we are 100% commission.

You need to know the cultures involved, the income levels involved, who would be likely to rent your unit and what they would do with it and how likely they are to stay and not cause problems.There is no mathematical formula that figures that into the equation, so to speak. 

There may be some mathematical formula out there that proves a certain font/ font size/ color/ sign color will allow the client to see better.

What you need is intimate market knowledge specific to the particular property, not some fantasy magical universal mathematical formula to apply to all property components in all properties.The value of real estate is a function of the whole.

After reviewing everyone's input I have decided to go with the mathematical approach identified by @Rajib Garu and @CJ M.At the end of the day, money pays the bills not people and math does not lie.

Mathematically the federal government must run a deficit at least equivalent to the trade deficit in order for the private sector to achieve sustainable growth.

This will cause panic to be heightened. https://finance.yahoo.com/news/hell-coming-mathematical-proof-185019616.htmlSo I freaked out on Friday and asked for a massive price reduction or I will walk away.

I just don't DO them because it's a mathematically bad idea.