I acknowledge what you say and mathematically it makes sense in a decent way but by having a paid off duplex I live in my return isn't only the duplex. it's the margages I don't have to pay the income I get to keep and my tenant paying for my utility's and gas allowing me to save 90 percent of my income putting me in a ever more advantageous position. any propertys past this however it makes more sense to leverage. just to me at least I need my primary paid off I have seen to many people struggle to pay there bills

From Canada I will try to put together a kind of an apartment Bible in the book form.This will be not hot air but all mathematical ratios starting with a mortgage, income,expenses, and residue or cash flow for the month and year end.The illustration will be all real and nothing with if's like there are so many programs available on the net.At he end the reader if followig all this will derive to his/hers net worth at the year end There will be nothing missing in order how to purchase, manage and dispose of such equity.Let me know if anything like this exists.

Thanks for the reply, I went to school for Mathematics with a minor in Computer Science and now work in Software Engineering so hopefully that will qualify me!

This plan is mathematically possible which is why I know I will find an investor fast. 

Mathematically, not every house will be a winner.

@ Ned Carey Now that I think about it from a mathematic perspective, even if I did roll say 6k of closing cost into the loan, in 30 years i'm paying 6300 back in additional interest, not terrible. (6k x .035 x 30)

Many buyers paid too much for their homes, didn't understand the underlying mathematics involved, didn't understand the financial instruments they were using, used their properties like ATMs, and didn't understand enough about business and economic cycles to filter through all of the "buy buy buy . . . it's always a great time to buy" noise spewed by many others (including many RE pros) who also were equally clueless.The "no down-payment equals no 'skin in the game'" argument is a non sequitor.

A whole area of mathematics is dedicated to solving that type of actuarial question.

That is just basic mathematics.  

Fortunately, the answer to this one is simple mathematics.