# CumPrinc

## CumPrinc(rate, nper, pv, start_per, end_per, type)

The cumulative principal received on an annuity (with periodic payments and constant interest rate) between «start_per» and «end_per» inclusive. A negative number represents cumulative principal paid.

Parameters:

«Rate»
The interest rate per period.
«NPer»
The total number of periods in the annuity's lifetime.
«Pv»
The present value.
If you receive a loan, this is the loan amount as a positive number.
If you give someone a loan, this is a negative number.
«Start_per»
First period included in the sum.
«End_per»
Last period included in the sum.
«Type»
(Optional) Indicates whether payments are at the beginning of the period.
`True` = Payments due at beginning of period, with first payment due immediately.
`False` = Payments due at end of period. (default)

Returns:

`Index n := start_per..end_per Do Sum(PPmt(rate, n, nper, pv, 0, type), I)`

## Library

Financial Functions

## Examples

Five years ago, you took out a 30-year fixed rate mortgage at a rate of 6.5% for an initial loan of \$350K. How much equity have you paid for during the first five years?

`-CumPrinc(6.5%/12, 30*12, \$350K,1, 5*12) → \$22,361.58`