Calculates the cumulative principle paid on an investment over multiple payment periods. This is done based on a constant interest rate and periodic payments with constant amounts.
CUMPRINC(rate: Number, numberofperiods: Number, presentvalue: Number, firstperiod: Number, lastperiod: Number, paymentsatthebeginningofperiod: Boolean) => Number
Parameter  Description 
Rate  The interest rate 
Number of periods  The number of payments to be made 
Present value  The current value of the annuity. 
First period  The number of the payment period to begin the cumulative calculation. 
Last period  The number of the payment period to end the cumulative calculation. 
Payments at the beginning of period  Whether payments are due at the end (false) or beginning (true) of each period 
Formula  Return value 





