ParThe cash flow sign convention
Financial calculators track which way money moves. Money you receive is positive; money you pay out is negative.
The rule
Pick a point of view, usually yours, and stick to it. A loan you take out is money in, so PV is positive and the payments are negative. A deposit is money out, so PV or PMT is negative and the balance you withdraw later, FV, is positive.
CHS changes the sign of the number in the display. Use it after typing an amount that leaves your pocket.
Why it matters
The time-value equation balances money in against money out. If every amount has the same sign, there’s nothing to balance, and the calculator shows an error instead of an answer.
When an answer comes out negative, read it as money you pay, not as a mistake.
Examples
Mortgage: PV +350,000, PMT −2,212.24. Savings plan: PMT −500, FV +260,463.33. Bond purchase: PV −96.50, coupons and redemption positive. Retirement: PV −800,000, PMT +4,657.31.