The most common errors in TVM questions come from wrong P/Y or C/Y settings and sign confusion. Get these right and the solver always works.
In short: In the finance solver, P/Y is the number of payments per year and C/Y is the number of compounding periods per year, and cash flows follow a sign convention: money you pay out is negative and money you receive is positive. Getting these settings and signs right matters more than the keystrokes.
When you'd use this
The compounding frequency (C/Y) is different from the payment frequency (P/Y), e.g. annual interest with monthly payments.
Your answer comes out negative (or the wrong size) - almost always a sign convention issue, not a wrong method.
Setting up a loan (money received, PV positive) versus an investment (money paid in, PV negative) correctly.
Double-checking a TVM answer that looks implausible before writing it down.
Steps (the same on every model)
P/Y = payments per year; C/Y = compounding periods per year. They are often equal but not always.
N = total number of payment periods (not years). For 5 years of monthly payments: N = 60.
Sign convention: money leaving your pocket is negative; money received is positive. For a loan: PV = +loan amount (received), PMT = −repayment (paid out), FV = 0 (fully repaid).
Here's a real IB-style question that uses exactly this technique.
HardCalculatorPaper 2[4 marks]
A loan of $8000 is taken out at a nominal annual interest rate of 7.2%, compounded monthly, to be repaid in equal monthly instalments over 4 years. Find the monthly repayment, to 2 decimal places.
$192.31
Mark it
Correct4 / 4 marks
Worked solution & mark scheme:
M1 N = 48, I% = 7.2, PV = 8000, P/Y = C/Y = 12
A1 PMT = $192.31
Common questions
When would I need to set P/Y, C/Y and the sign conventions in the finance solver in IB Maths?
The most common errors in TVM questions come from wrong P/Y or C/Y settings and sign confusion. Get these right and the solver always works. The compounding frequency (C/Y) is different from the payment frequency (P/Y), e.g. annual interest with monthly payments. Your answer comes out negative (or the wrong size) - almost always a sign convention issue, not a wrong method.
How do I set P/Y, C/Y and the sign conventions in the finance solver?
1. P/Y = payments per year; C/Y = compounding periods per year. They are often equal but not always. 2. Monthly compounding, annual payment: P/Y = 1, C/Y = 12. Monthly compounding, monthly payment: P/Y = 12, C/Y = 12. 3. N = total number of payment periods (not years). For 5 years of monthly payments: N = 60. 4. Sign convention: money leaving your pocket is negative; money received is positive. For a loan: PV = +loan amount (received), PMT = −repayment (paid out), FV = 0 (fully repaid). 5. For a savings account: PV = −initial deposit (paid in), PMT = −regular deposit (paid in), FV = +final balance (received). 6. To solve for any variable: enter all known values, leave the unknown as 0, move the cursor to the unknown and solve.
What should I watch out for when I set P/Y, C/Y and the sign conventions in the finance solver?
If the solver gives a strange answer, check the sign of PV and PMT first - they are almost always the culprit. For simple lump-sum compound interest (no regular payments): set PMT = 0. For an annuity (regular payments, no lump sum): set PV = 0.
How are marks awarded when I set P/Y, C/Y and the sign conventions in the finance solver in an IB exam?
In the worked example on this page (4 marks, Paper 2), the marks are: M1: N = 48, I% = 7.2, PV = 8000, P/Y = C/Y = 12; A1: PMT = $192.31.
