Present value (PV) and future value (FV): FV = PV(1 + r)^n (compound interest forward); PV = FV/(1+r)^n (discount backward). r = discount/interest rate per period; n = number of periods. Example: FV=1000 after 3 years at 10%. PV = 1000/(1.1)³ = 751.31. Annuities: Series of equal payments at regular intervals. Present value of annuity: PV = A × [(1-(1+r)^(-n))/r]. Future value of annuity: FV = A × [((1+r)^n - 1)/r]. Where A = periodic payment. Exam tip: Distinguish between lump sum and annuity problems. Read timing carefully (beginning vs end of period). Use calculator for large powers efficiently.