What must you do to input a formula calculating the present value of payments?

To calculate the present value of future payments, accessing the Net Present Value (NPV) function and entering the required values is the appropriate approach. The NPV function takes into account the time value of money, which is a critical concept in financial calculations. By applying this function, you can discount future payments back to their present value using a specified interest rate. This method allows for a more accurate calculation by considering both the timing and the amount of cash flows, which cannot be achieved through simple addition or multiplication.

The other options would not yield a correct present value calculation. Simple addition does not reflect the time value of money, leading to an inaccurate total. Multiplying total payments by the interest rate does not calculate present value; it merely provides a figure based on interest, which is not reflective of the present value concept. Similarly, subtracting each payment from the interest rate would yield nonsensical results and does not contribute to determining present value. Thus, option A is the only effective method for calculating the present value accurately.