So it's overstated by a factor of nearly 4, which tallies with my commonsense that water supply only (not heating; that's individual) for a 1/2BR unit shouldn't be $57 per month.So given this piece of mathematics, I'm pretty confident I can get the expenses lower than stated.

The 2% Rule is the same thing as using the 50% Rule and applying a 12% Cap Rate on the annual NOI.I was looking at some properties and noticed I got the same value using the 2% rule and using the 50% for an estimate of NOI and happened to be using a 12% Cap.Being a math dork I did write it out symbolically and they both reduce to the same mathematical equation (Which BTW is just multiply the monthly rent by 50).

But it is not 90/10 - the notion is correct, but it's mathematically incorrect, because there are literally over a couple thousand agents in Milwaukee that do less than 5 transactions a year.

You can if you like the house, mathematically it might not be the best option but not all decisions have to be math based. 

In the world of mathematics, you can NOT use a number unless it is accurate. 

This looks like an excel function, but what is the actual mathematical equation?

Oh okay, now the lender has some security just in case you can't pay back the loan...Lets say you are purchasing a property for $100k and for sake of argument and mathematically simplicity the down payment is zero. 

Familiarize yourself with all the mathematical ways to approach prospective deals.  

I have previous experience in the marketing field, but most recently have been teaching various mathematics courses at a local high school.

If you reinvest at 3% or greater you’re always better off keeping the low interest loan as long as possible.The reason people believe these strategies that defy mathematical analysis is 1.