Calculates the interest paid (or received) for the specified period of a loan (or investment) with even principal payments.
The interest rate for the investment.
The period for which you want to find the interest, and must be between 1 and Nper.
The total number of payment periods for the investment.
The present value of the investment. For a loan, Pv is the loan amount.
Contributors: Alberto Ferrari, Marco Russo
Microsoft documentation: https://support.microsoft.com/en-us/office/ispmt-function-fa58adb6-9d39-4ce0-8f43-75399cea56cc