Banking

savings account growth, FD and RD calculations

Indian FDs usually compound quarterly — so a 7% annual rate effectively earns ~7.18% (small but compounding adds up over decades).

Loans

home mortgage, car loan, personal loan EMI

Home-loan EMI uses compound interest amortisation. A ₹50 lakh loan at 9% over 20 years means you pay back roughly ₹1.08 crore — interest alone is ₹58 lakhs.

Credit cards

revolving balance and APR calculations

Revolving credit at 36% APR compounds monthly. A ₹10000 unpaid balance becomes ₹14258 in just one year if you only pay the minimum.

Government bonds

coupon rates and yield-to-maturity

A 10-year G-Sec at 7.2% yield pays interest semi-annually. Yield-to-maturity uses compound interest to compare bonds with different coupons.

Insurance

time-value of money in premium calculations

Endowment policies advertise "guaranteed maturity" — but the implied rate is often only 4–5% CI, much lower than equity SIPs.

Exams

CI vs SI difference problems are CAT / Bank exam staples

CI vs SI difference questions appear in almost every Bank PO and SSC paper. The 2-year and 3-year shortcut formulas save real time.