In the calculations below, remember the sign convention! If you have an error on your HP12C, either that or omitted data is the most likely cause. Remember also that the interest rate must be consistent with the number of periods on the HP12C. If you have 12 percent annual interest, and are using 12 periods per year, you would enter 1 into [i] (or you could enter 12 [g] [i]).

To calculate First clear Next enter Next enter Next enter Next enter Push for result
Future value fX<>Y and fCLX # n # i (consistent with n) #PMT (if any). Annuity payments # PV (if any). Single payments now FV
Present value fX<>Y and fCLX # n # i (consistent with n) #PMT (if any). Annuity payments # FV (if any) . Single payments at time n PV
Interest rate fX<>Y and fCLX # n #PMT (if any). Annuity payments # PV (if any). Single payments now # FV ( if any). Single payments at time n i
Annuity payment fX<>Y and fCLX # n # i (consistent with n) #PV (if any). Single payments now # FV (if any)< /i>. Single payments at time n PMT

## To amortize a loan with your HP12C

Do the steps for annuity payment as shown above. Then enter 0 into n. Enter # (the number of periods you want to amortize) followed by fn [ amort]. For example, to calculate interest and principal paid for the first five periods of a loan, enter 5 amort:

• The interest paid for the interval you amortized is shown on the screen.
• To show the principal paid for the interval, press x>.
• To show the remaining balance of the loan, press RCL PV.

If you had 12 months of payments on your house loan after the short first interval of 5 payments above, youâ€™d press 12 amort. The first calculation would amortize 5 months of the loan, and the second calculation would amortize 12 months of the loa n. Press # amort for each subsequent interval you wish to amortize using the HP12C keys.

## To calculate IRR and NPV with your HP12C

Enter the cash flows as follows, remembering the sign convention:

• Clear previous data on the HP12C by pressing f [X<>Y] and f [CLX].
• Enter the cash flow at time zero using g [PV] or (CF0).
• Enter subsequent cash flows using g [PMT] or (CFj).
• If a cash flow is repeated, enter the number of times it is repeated (including the first time you just entered) using g [FV] or (Nj). For example, three equal flows in a row would be entered as 3 (Nj).
• When you have entered your last cash flow into the HP12C :
• If you are calculating an NPV, enter your interest rate as # i (consistent with interval between cash flows) followed by f [PV] (NPV).
• If you are calculating an IRR, enter f [FV] (IRR).