Is there a formula or something to calculate the value of a commercial rental property.

If you have the right formula you should be able to cut out one apartment and pay for it with the other two but you know you don't get to depreciate all three apartments and expenses, right?

Much of the math was done automatically on excel with formulas.

@Brian Maida;the excel formula for FUTURE VALUE=FV(C5;C4;C6;C7) in cell d8 for a 1% return per year for 20yrs

On the seller's side, operators or investors more commonly state an option price, usually they seek all they can get, but that's not always a great idea, as reasonableness comes into play as to that formula mentioned.

I frankly dont buy anything giving me less than 15%, 10% is a non-starter. 20% is a guaranteed purchase unless issues are around with the property(major repairs due in less than 5 years) or the neighborhood itself(major employer leaving) Thank you @Christian Hutchinson for your formula, I just want to clarify one thing.

It wouldn't surprise me if sites like RENAV just work the amortization formula based on the last loan and terms.

If you are looking for a quick method to provide a ballpark estimate, there is an easy formula. 

Account Closed we did 3.5% down because we did an FHA loan.As for LTV, I did the flip formula(70% x ARV - Scope of work = MAO) to come up with the asking price.

Saving and investing your additional income will also be an important part of this formula.