Press the "2nd" key to access the calculator's secondary functions and then hit the "FV" key to clear out any previous calculations or numbers that you have stored.
Enter in the total amount that you are working with first. For example if you need to calculate how much you want to initially invest in order to accrue $20,000 through interest alone you would type in "20,000."
Type in the interest rate next without pressing any other buttons, such as "5" for a 5% interest rate. Hit the "I/Y" button to specify that the number will be interested accrued. Press the "2nd" key and then press the "I/Y" key again so you can specify that the interest is accrued over a 12 month period. Enter in the number one and then the number two and hit "Enter."
Hit the "2nd" key again and then press the "CPT" key to return to the main screen and end specifying the interest rate. Type in the number of years remaining until you need the original amount you typed in, such as "4" for four years. Press the "2nd" key and then press the "N" button to break it down into months.
Press the "PV" button to complete the calculation and get the total amount you need to initially invest to reach your desired amount in the specified time frame with the interest rate you entered.