Calculates the interest paid at a particular period of an investment.

**Sample Usage**

ISPMT(15%,2,5,1000)

**Syntax**

ISPMT(rate, period, total_periods, present_value)

- rate - The annualized rate of interest.
- period - The period for which you want to find the interest payment.
- total_periods - The total number of payment periods.
- present_value - The present value of the annuity.

**Examples**

ISPMT(15%,2,5,1000) calculates the interest paid in the second of five periods.

**Notes**

- period must be number between 1 and total_periods.
- Ensure that consistent units are used for rate, period and total_periods.