RPN financial calculator guides

Worked problems with every keystroke and every display, for loans, savings, cash flows, bonds, depreciation, dates and statistics. The steps follow the classic gold-key financial calculator layout, and every answer here is checked against Par’s engine.

Loans and mortgages

How to calculate a mortgage paymentWork out the monthly payment on a 30-year mortgage in five keystroke steps with an RPN financial calculator, with the answer, the reasoning and the common mistakes.
How to calculate the total interest on a loanFind the total of all payments and the total interest over the life of a mortgage or loan with a few RPN keystrokes, using the payment the calculator already solved.
How to calculate a car loan paymentSubtract the down payment and solve for the monthly car payment in one RPN chain, with the keystrokes, the answer and how to compare loan offers.
How much can I borrow for a given payment?Turn a monthly budget into the largest loan it can pay off, by solving for PV on an RPN financial calculator. Keystrokes, answer and explanation.
How long will it take to pay off a balance?Find how many months it takes to pay off a balance at a fixed payment, and the smaller final payment, with RPN keystrokes on a financial calculator.
How to find a loan’s interest rate from its paymentSolve for the interest rate when you know the loan amount, payment and term, then turn the monthly rate into an annual rate, on an RPN financial calculator.
How to calculate APR including feesWork out the true APR of a mortgage with closing costs or points by solving for the rate on the amount you actually receive. RPN keystrokes and answer.
How to calculate a balloon paymentFind the balloon payment due when a long-amortizing loan comes due early, by solving for FV after the payments made. RPN keystrokes, answer and explanation.
How to find the remaining balance on a loanUse AMORT to find the interest, principal and remaining balance after any number of loan payments on an RPN financial calculator. Keystrokes and answer.
How to build an amortization schedule year by yearBuild an annual amortization schedule, with interest, principal and balance for each year of a mortgage, by repeating 12 f AMORT on an RPN financial calculator.
How much faster do extra payments pay off a mortgage?See how many years an extra monthly payment takes off a mortgage by solving for n with a larger payment on an RPN financial calculator.
How to calculate a lease payment with a residualWork out a monthly lease payment with a residual value and payments in advance, using BEG mode on an RPN financial calculator. Keystrokes and answer.

Saving and investing

How to calculate compound interestFind what a lump sum grows to with compound interest using n, i, PV and FV on an RPN financial calculator, with keystrokes, the answer and monthly compounding.
How much will monthly savings grow to?Find the future value of a fixed monthly deposit, such as a retirement or college fund, with RPN keystrokes on a financial calculator.
How much do I need to save each month?Solve for the monthly saving needed to reach a target amount by a given date, with RPN keystrokes on a financial calculator.
How to calculate CAGRFind the compound annual growth rate between a starting and ending value by solving for i on an RPN financial calculator. Keystrokes and answer.
How long does it take to double your money?Work out how long an investment takes to double at a given rate, on an RPN financial calculator, and why n rounds up. Compare with the rule of 72.
How much monthly income will my savings give?Find the monthly withdrawal a retirement nest egg supports for a set number of years, with payments at the start of each month, on an RPN financial calculator.
How to calculate present valueFind how much you need to invest today to have a set amount later, by solving for PV on an RPN financial calculator. Keystrokes, answer and explanation.
Lump sum or annual payments?Compare a lump sum with a stream of yearly payments, such as a pension or lottery payout, by finding the present value of the payments on an RPN calculator.

Interest rates and percentages

How to convert a nominal rate to an effective annual rateTurn a nominal interest rate compounded monthly into an effective annual rate (APY) with the financial keys of an RPN calculator. Keystrokes and answer.
How to calculate simple interestWork out simple interest on a 360-day and a 365-day basis with the INT function of an RPN financial calculator, with keystrokes and answers.
How to calculate percent changeFind the percentage increase or decrease between two numbers with the Δ% key of an RPN financial calculator. Keystrokes, answer and examples.
Percentages, discounts and percent of totalUse the % and %T keys of an RPN financial calculator to take a discount, add sales tax, and find what share of a total a number is.

NPV and IRR

How to calculate NPVEnter uneven cash flows with CFo and CFj and find the net present value at a discount rate with NPV on an RPN financial calculator. Keystrokes and answer.
How to calculate IRRFind the internal rate of return of uneven cash flows with f IRR on an RPN financial calculator, with keystrokes, the answer and how to read it.
How to enter repeated cash flows with NjEnter runs of identical cash flows with Nj to find NPV and IRR quickly on an RPN financial calculator. Keystrokes, answer and the register limits.

Bonds

How to calculate a bond’s priceFind the price of a semiannual coupon bond for a given yield, plus accrued interest, with f PRICE on an RPN financial calculator. Keystrokes and answer.
How to calculate yield to maturityFind the yield to maturity of a semiannual coupon bond from its price with f YTM on an RPN financial calculator. Keystrokes, answer and explanation.

Depreciation

How to calculate straight-line depreciationFind yearly straight-line depreciation and the remaining depreciable value of an asset with f SL on an RPN financial calculator. Keystrokes and answer.
How to calculate sum-of-the-years’-digits depreciationFind sum-of-the-years’-digits depreciation for any year of an asset’s life with f SOYD on an RPN financial calculator. Keystrokes and answer.
How to calculate declining-balance depreciationFind double-declining-balance (200%) depreciation with f DB on an RPN financial calculator, with keystrokes, answers and how to set other factors.

Dates

How to count the days between two datesCount the days between two dates on both an actual and a 30/360 basis with g ΔDYS on an RPN financial calculator. Keystrokes and answer.
How to find the date a number of days from nowAdd or subtract days from a date and see the weekday with g DATE on an RPN financial calculator, for due dates, deadlines and notice periods.
How to find the day of the week for any dateFind which day of the week any date fell on or will fall on, by adding zero days with g DATE on an RPN financial calculator.

Statistics

How to calculate the mean and standard deviationEnter data with Σ+ and find the mean and sample standard deviation with g x̄ and g s on an RPN financial calculator. Keystrokes and answer.
How to calculate a weighted averageFind a weighted average, such as the average price paid for shares bought in lots, with Σ+ and g x̄w on an RPN financial calculator.
How to forecast with linear regressionFit a straight line to data and forecast the next value, with the correlation coefficient, using Σ+ and g ŷ,r on an RPN financial calculator.

RPN basics

How to use an RPN calculatorLearn Reverse Polish Notation in five minutes: how ENTER and the four-level stack replace parentheses and the equals key, with worked keystrokes.
Powers, roots and logarithmsRaise numbers to powers, take nth roots and logarithms, and show more decimal places on an RPN financial calculator, with keystrokes and answers.

Concepts

What is RPN?Reverse Polish Notation explained: where it came from, how the stack works, and why finance professionals still use RPN calculators.
The time value of money: n, i, PV, PMT and FVThe five time-value-of-money variables explained, how they describe any loan, savings plan or annuity, and how to solve for any one of them.
The cash flow sign conventionWhy a financial calculator shows payments as negative numbers, how to choose signs for PV, PMT and FV, and how to fix the error you get when signs are wrong.
BEGIN or END mode?When to use BEGIN or END payment mode on a financial calculator, what each means, and how much the choice changes payments and values.
NPV vs IRRNet present value and internal rate of return compared: what each measures, when they disagree, and which to trust when they do.
Nominal vs effective interest ratesThe difference between nominal and effective interest rates, APR and APY, why compounding makes them differ, and how to convert between them.
Actual vs 30/360 day countsWhat actual and 30/360 day counts mean, where each is used in loans and bonds, and how to compute both at once on an RPN financial calculator.