Plot the future value curve for each year for the next twenty years for an investment of $1000 today. Then create a form control spin button to show what happens to the curve from 0% return to 25% return with 5% increments for each click. I have discovered the cell controlled must be an integer, so you will need to do some manipulation. Also fix you're your vertical axis to $90,000 so you can actually see the curve moving rather than having the scale on the axis change.