NPV
Purpose 
Returns the net present value (NPV) of a series of unequal payments made at regular intervals, assuming a fixed interestRate per interval.
Format 
NPV(payment;interestRate)
Parameters 
payment - a repeating field containing unequal payment amounts, or an expression that returns a reference to one.
interestRate - interest rate.
Data type returned 
number
Description 
Use this function to calculate NPV. For example, if someone borrows money from you and pays you back in unequal amounts over a period of several years, you can use the NPV function to calculate the result.
Equation
Examples 
NPV(Loan;.05) returns 156.91277445..., when the repeating field, Loan, contains -2000 (the initial payment), 600, 300, 500, 700, and 400. The result (156.91277445...) is the actual profit in today’s dollars that will be realized from this transaction.
NPV(Amounts;.10) returns 16758.35604870..., when the repeating field, Amounts, contains -5000 (the initial investment), 10,000, 0, 10,000, and 10,000.
If you want each return value to return 2 decimal places, surround the current formulas with the correct Round function: Round(Current Formula;2).
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas