Need help on formulas for Excel to calc selling value of note

Hi All,

I have the 10bii calculator app on my iPhone that has an "easy mode" to determine the purchase price of  a note based upon entering 1. the monthly payment, 2, the remaining term in months, 3. the desired annual % return, and 4. the ending balance (which would be $0 if no balloon). 

I want to set this up on an excel spreadsheet that I'm creating for some financial projections. Does anyone have any thoughts on what formulas to use to recreate this on a spreadsheet, or a website that provides any tips/instructions?

Thanks