README.md

NPER(rate, PMT, PV, FV, type).
Returns the number of periods for an investment based on periodic,constant payments and a constant interest rate.

* Rate is the periodic interest rate.

* PMT is the constant annuity paid in each period.

* PV is the present value (cash value) in a sequence of payments.

* FV (optional) is the future value, which is reached at the end of the last period.

* Type (optional) defines whether the payment is due at the beginning (1) or the end (0) of a period.