It's simply one year, 12 months, divided by project time, then multiplied by your return for that project. ie. if your flip takes 4 months and you made a 10% return on your money, your annualized return would be 30%. 12/4 = 3, 3 x 10% = 30%.  

Couple vital issues you are missing:Reserve funds 12 to 24 months multiplied by all you debts plus the subject PITI fully amortized plus HOALender by lender are licensed in some states and not othersMinimum loan amounts apply lender by lender (they don't like small loans as hits HIGH Cost and HOEPA loan laws ceilings).They want a property ready to rent on day one.

I use enough leverage such that the portfolio can get a real multiplier and make the most of the long-term hoped-for appreciation rates, but not so much that I risk needing to commit more and more capital to operate the business - I also maintain a cash cushion, which reduces my risk of ruin, but hurts my returns. 

I can pay I/O if I want.I personally use the AIO to multiply houses but I have clients that simply want to use this to pay off the primary mortgage cheaper and faster.

That will give you a percentage that you can use to multiply by your prospective new purchase price and you'll be about there. 

When filing your Hotel Room Occupancy Tax return, you should include all of the rent charged on Line 5 and multiply that by 5.875%.

Weekly Supp. 822b, (Orange County Court, 9th Judicial Circuit, 2008), the Court awarded a multiplier of 2.0 to a prevailing tenant.

Our appraiser remarked that our comps had Gross Rent Multipliers of 93-119; and that 90 was typical for the market. 

Or are you looking at COGS multiplied by mark up, plus all costs/fees, plus profit = sales price?

Sometimes lenders will go by the gross cash multiplier method when appraising the units, especially with multi family places.