NPER (Number of Period) Returns the number of periods for an investment based on periodic, constant payments and a constant interest rate.
        
Example
                 
NPER = 1 / log(Rate + 1) * log( (-Fv * Rate + Rate * PMT + PMT ) / (Rate * PMT + Rate * PV + PMT ) )

             FV      =    Future Value
             PV      =    Present Value
             Rate   =    Interest Rate per period
             Nper   =    Number of periods
             type   =    Payment At (Beginning = 1 , End = 0)
             pmt   =    Payment Value

             Example

         Future value 1,000,000 Bath, Annual interest rate 0.5 % , Payment made each period 25,000 Bath, At the end of the period

         Solution
         NPER = 1 / log(10% + 1) *log ( ( - 1,000,000 * 10% + 10% * -25,000 + -25,000 ) / (10% * -25,000 + 10% * -100,000 - 25,000 ) )
         NPER = 13.36          Read more »