2 Develop a single spreadsheet that allows you to calculate any of the P|A, A|P F|A, or A|F, factors. For each cell where the calculation is performed, place above it a small control panel that allows you to enter whatever numbers you need to perform the calculation. For example, for the F|A factor, your control panel needs to include i and n. Test each of your factors against the tables in Appendix A to ensure they work right. Keep this handy. It will be useful to you.