Both TI-Nspire and Casio ClassPad include dedicated Finance Solver (or TVM Solver) applications that solve for any one of the five financial variables when the other four are known.
| Variable | Meaning |
|---|---|
| $N$ | Number of payment periods |
| $I\%$ | Annual interest rate (as a percentage) |
| $PV$ | Present value (initial principal, entered as negative for loans) |
| $PMT$ | Payment per period (negative if outgoing) |
| $FV$ | Future value (balance at end, 0 for fully repaid loans) |
Find the monthly repayment for a \$15,000 car loan at 7.2% p.a. for 4 years.
TVM inputs:
- $N = 4 \times 12 = 48$
- $I\% = 7.2$
- $PV = 15000$ (positive; money received)
- $FV = 0$ (fully repaid)
- Payments per year = 12
Solve for $PMT$. CAS returns: $PMT \approx -360.69$.
Monthly repayment $\approx \$360.69$.
Saving \$200 per month at 4.8% p.a. (compounding monthly) for 5 years.
TVM inputs:
- $N = 60$
- $I\% = 4.8$
- $PV = 0$ (starting from nothing)
- $PMT = -200$ (negative: money going out)
- Solve for $FV$
CAS returns: $FV \approx \$13{,}491$.
CAS spreadsheet or list functions can iterate the recurrence $A_{n+1} = A_n(1+r) - d$ to produce a full amortisation table showing:
- Balance at start of period
- Interest charged
- Repayment
- Closing balance
This helps verify answers and analyse specific periods.
Excel/Google Sheets functions:
- =PMT(rate, nper, pv) — monthly payment
- =FV(rate, nper, pmt, pv) — future value
- =PV(rate, nper, pmt, fv) — present value
- =NPER(rate, pmt, pv, fv) — number of periods
Different CAS tools use different sign conventions. The universal rule: money flowing out is negative, money flowing in is positive. Apply this consistently.
STUDY HINT: Practise setting up TVM problems before the exam. Know whether $N$ is in months or years and whether to set payments per year. A wrong frequency is the most common TVM error.
EXAM TIP: Record all inputs alongside your CAS output. If your answer is wrong but inputs are correct, you may still receive method marks. Never submit CAS output without showing what was entered.
