How to use the finance (TVM) solver on the Casio fx-CG50, TI-84 Plus CE and TI-Nspire CX II
On the fx-CG50: MENU → FINANCIAL → F2 (COMPOUND INTEREST).On the TI-84 Plus CE: apps → 1: Finance → 1: TVM Solver.On the TI-Nspire CX II: menu → Finance → Finance Solver.
Compound interest, loans, annuities and depreciation with the time-value-of-money solver (IB AI). Exact keystrokes for the fx-CG50 first, then the other calculators, a worked example you can check your answers against, the mistakes that cost marks, and the same thing in Desmos.
When you need it
AI SL and HL: compound interest, the value of an investment, loan repayments, the time to reach a target, and amortisation. The IB accepts the TVM solver as working if you write down the values you entered (N = 72, I% = 4.5, PV = −5000, …).
Practise it: SL AI financial mathematics · SL AI financial maths · SL AA financial maths.
Which IB course and paper
| Course | GDC papers | What you use it for |
|---|---|---|
| AA SL | Paper 2 (Paper 1 is calculator-free) | Compound interest and depreciation (financial uses of geometric sequences). |
| AA HL | Papers 2 and 3 (Paper 1 is calculator-free) | As SL. |
| AI SL | Papers 1 and 2 | Compound interest, depreciation, loans, annuities and amortisation. |
| AI HL | Papers 1, 2 and 3 | As SL. |
A GDC is allowed on every AI paper and on AA Papers 2 and 3; AA Paper 1 is calculator-free, so learn the method by hand as well.
Topic notes: Financial maths (AI SL) · Geometric sequences and compound interest (AI SL).
Keystrokes on your calculator
Pick your calculator: the page remembers it next time.
Finance (TVM solver) on the Casio fx-CG50
Written for OS 3.80 (menus unchanged from OS 3.60 onwards as far as we can tell). Casio fx-CG50: graphic (GDC).
Watch the key presses on the fx-CG5010 presses, one at a time
The walkthrough needs JavaScript. The same key presses are in the numbered steps below.
- MENU, then choose FINANCIAL (highlight it and press EXE).
- F2 (COMPOUND INTEREST).
- Enter n = 72, I% = 4.5, PV = −5000, PMT = 0, FV = 0 (to be found), P/Y = 12, C/Y = 12, with EXE after each.
- Press the key for the unknown: F5 (FV). The result is shown; EXIT (or F1 REPEAT) returns to the inputs.
- Loan: n = 60, I% = 6, PV = 20000, FV = 0, P/Y = 12, C/Y = 12, then F4 (PMT): −386.66 (negative: money paid out). For n use F1 (n).
- F6 (AMT) after a loan gives the amortisation: the interest and principal in a given payment range.
- Payment timing (beginning or end of each period) is in SHIFT MENU (SET UP) → Payment: BGN / END. The IB normally uses END.
- The other Financial menus: F1 SIMPLE INTEREST, F3 CASH FLOW (NPV, IRR), F4 AMORTIZATION, F5 CONVERSION (nominal ↔ effective rates).
Finance (TVM solver) on the TI-84 Plus CE
Written for OS 5.8.x. TI-84 Plus CE: graphic (GDC); also the TI-84 Plus CE Python / CE-T Python Edition.
Watch the key presses on the TI-84 Plus CE5 presses, one at a time
The walkthrough needs JavaScript. The same key presses are in the numbered steps below.
- apps → 1: Finance → 1: TVM Solver.
- N = 72, I% = 4.5, PV = −5000, PMT = 0, FV = 0, P/Y = 12, C/Y = 12, PMT: END.
- Move the cursor to FV and press alpha enter (SOLVE). A square marks the solved value.
- The Finance app's Σ Int( and Σ Prn( functions give interest and principal paid over a range of payments.
Finance (TVM solver) on the TI-Nspire CX II
Written for OS 6.x. TI-Nspire CX II: graphic (GDC), non-CAS (the CX II CAS is a different model: check the exam rules before using one).
- Calculator page: menu → Finance → Finance Solver.
- Enter N, I(%), PV, Pmt, FV, PpY, CpY; leave the unknown blank or 0.
- tab to the unknown and press enter to solve it.
- amortTbl( in the same menu builds an amortisation table.
For teachers: Show on the board Print a keystroke card Teaching GDC skills
Worked example
(a) $5000 is invested at 4.5% per year compounded monthly. Find its value after 6 years. (b) A $20 000 loan at 6% per year compounded monthly is repaid monthly over 5 years. Find the repayment and the total paid. (c) How long does money take to double at 5% compounded quarterly?
Answers (checked with Python)
(a) FV = $6546.52. (b) PMT = $386.66 per month; total paid 60 × $386.66 = $23199.60. (c) N = 55.8 quarters, so 14 years (13.9 years).
Now try it on an exam-style question
Use the keystrokes above on IB-style financial mathematics questions. Free to try, no sign-up.
Common calculator mistakes
- Signs: money you pay (a deposit, a repayment) is negative; money you receive is positive. PV and FV with the same sign gives an error or nonsense.
- N is the number of periods, not years: 6 years monthly is 72.
- P/Y and C/Y must match the question (monthly payments with interest compounded yearly: P/Y = 12, C/Y = 1).
- Rounding money to 3 s.f.: give money to 2 decimal places (or as the question says).
- Not writing down the inputs: show N, I%, PV, PMT, FV, P/Y, C/Y as your working.
- Money: give amounts to 2 decimal places (or the nearest whole unit if the question says so), not 3 s.f.
If you get an error
fx-CG50: Ma ERROR
Ma ERROR Casio's Math ERROR: the result is outside the allowable calculation range, or you are trying to do an illegal mathematical operation, such as dividing by zero. Check: Look for a zero denominator, sin⁻¹ or cos⁻¹ of a number bigger than 1 (often a wrong side or angle in the sine or cosine rule), the log of 0 or of a negative number, and a value stored in a variable earlier that you forgot about. Fix: Casio's advice: check your input values and change them so the result is within the allowable range.
TI-84 Plus CE: ERR:DOMAIN, ERR:SYNTAX
ERR:DOMAIN A value given to a function or instruction is outside the values it accepts. In a regression, TI says it means the data do not suit the model you chose. Check: Is every input allowed? σ must be positive, p between 0 and 1, and sin⁻¹ or cos⁻¹ needs a number from −1 to 1. Exponential and power models need positive data. Fix: Change the value that is out of range, or choose a model that suits the data.
ERR:SYNTAX The command contains a syntax error: a misplaced function, argument, bracket or comma. Check: TI points out that subtract − and negative (−) are different keys, and using the wrong one causes this error. Then check the brackets and commas. Fix: Find the misplaced function, argument, bracket or comma and correct it.
TI-Nspire CX II: Domain error, Syntax error
Domain error An argument must be in a specified domain, and this one is not (TI's example: rand(0)). Check: Is every input allowed? σ must be positive, p between 0 and 1, and sin⁻¹ or cos⁻¹ needs a number from −1 to 1. Fix: Change the value that is out of range.
Syntax error The syntax checker found a problem. Check: A missing bracket or comma. Fix: Correct the expression and try again.
Do it in Desmos
Not in the exam. Desmos is not an approved calculator for IB exams, so never rely on it for Paper 2. It is excellent for learning, checking a GDC answer and building graphs for your Internal Assessment (IA).
- Graph the value against time in years: y = 5000(1 + 0.045/12)^{12x}.
- Evaluate it at x = 6, or add y = 10000 and click the intersection to see when it doubles.
- Desmos has no TVM solver; the formula is the same one your GDC uses.
Open desmos.com/calculator (free, in any browser) and type:
y=5000(1+frac{0.045}{12})^{12x}5000(1+frac{0.045}{12})^{72}y=10000
Questions
Can I use a calculator for finance (TVM solver) in the exam?
In IB Maths you can use one approved GDC on every AI paper and on AA Papers 2 and 3, in exam mode. AA Paper 1 is calculator-free, so learn the method by hand as well.
What are the fx-CG50 keystrokes for finance (TVM solver)?
MENU, then choose FINANCIAL (highlight it and press EXE). Then F2 (COMPOUND INTEREST). Then Enter n = 72, I% = 4.5, PV = −5000, PMT = 0, FV = 0 (to be found), P/Y = 12, C/Y = 12, with EXE after each. The full steps and the other calculators are in the keystrokes section above.
Does this work on other calculators?
Yes. This page has keystrokes for the Casio fx-CG50, TI-84 Plus CE and TI-Nspire CX II. The worked example has the same answers on every model, so use it to check.
What should I write as working?
Write the maths, not the key presses: say what you are finding in normal notation (the equation, the probability statement or the integral), then the calculator's answer exact or to 3 significant figures unless the question says otherwise. Keep full accuracy in later parts.
More calculator skills
Sources
- Casio fx-CG50 Software User's Guide, OS 3.70 (PDF) : Casio fx-CG50, OS 3.80 (menus unchanged from OS 3.60 onwards as far as we can tell).
- TI-84 Plus CE guidebook (Texas Instruments) : TI-84 Plus CE, OS 5.8.x.
- TI-Nspire CX II guidebooks (Texas Instruments) : TI-Nspire CX II, OS 6.x.
- Desmos Help Center for the Desmos functions.
Menu names are taken from each manufacturer's manual for the models shown. Menus can move slightly between OS updates: if a screen looks different on yours, the manual for your version is the reference, and please tell us so we can update this page. A calculator with no tab here has no checked steps for this skill yet. Worked-example answers were recomputed independently in Python.