Need Financial Math Guru to Help Set Goals

[Gary West]

Hello All,

I need someone who is strong in math and or spreadsheets to help me with goal setting.

Here is the situation: I want to own (free and clear) 15 properties as soon as possible.

The first one will paid off in February 2014.
Then ill buy another and put 4k per month towards its pay off. (110k loan)

Rinse and repeat x15. Each time using the income from the previous properties to pay off the next one. Add 4k per month of my own money to the payments.

As you can see each property gets paid of at an increasing rate.

MY QUESTION: Will paying off other debt and using the extra money for investing slow my progress or speed it up?

My thoughts are to not worry about my current non mortgage debt and put all my cash into investments. Can you prove mathmatically that I should pay off debt first or even concurrently with investing? Can you show me the benefits of such?

Whats faster? Paying off debt (80k at 8%interest , 9 different loans w varying amounts) using a portion of my 4k per month investment budget or focusing on investment property soley?

Which path is best/faster for achieving the 15 properties free and clear?

Thanks so much.