One way:
If you have the following information:
A1: <annual interest rate>
A2: <number of years>
A3: <Principal amount>
A4: =PMT(A1/2, A2*2, A3)
The key is to make sure the rate and the periods are in sync - i.e., if
you have 6-month periods, you need to have 6-month rates.
