NPER
Basic Overview
Description  Calculates the number of periods necessary for a recurring investment based on an interest rate, the amount of payment per period, a present value, a future value and either ordinary annuity or annuity due (type) indicating whether payments are due at the beginning or the end of period. 

Signature  NPER('Rate', 'Pmt', 'Pv' [, 'Fv' [, "Type"]]) 
Parameters 

Notes 

Limitations 

Positive Costs/Payments
In case the costs or payments are entered as a positive number within your model, this function needs to be multiplied by (1).
Example
Rate (Interest Rate)  0.045/12 

Pmt (Payment per Period  Amount)  100 
Pv (Present Value)  5000 
Fv (Future Value)  0 
Type Payment at Beginning of Period (Annuity Due) = 1 Payment at End of Period (Ordinary Annuity) = 0  0 
Valsight Formula  NPER(Rate, Pmt, Pv, Fv, Type) 
Result  55.47 