Compound Interest (CI) basics: A = P(1 + r/100)^n where P = principal, r = rate, n = compounding periods. CI = A - P. Key concepts: interest earned on interest (exponential growth), compounds annually unless specified. Common traps: forgetting to use compound formula (not simple), misidentifying compounding frequency. Exam tips: identify compounding period (annual/semi-annual/quarterly/monthly). Time-saving: use calculator for powers. Compounding frequency: annual (n=1), semi-annual (n=2), quarterly (n=4), monthly (n=12). Applications: investments, savings accounts, mortgage calculations. Shortcut: recognize (1 + r/100) value, practice powers. Verification: CI ≥ SI (compound grows faster). Comparison: CI vs SI difference increases with time. Understanding CI foundation for investment analysis. Practice with various compounding frequencies.