Q: Save ₹50000 in 5 years at 8%. Find annual deposit into sinking fund. s_5 = ((1.08)⁵-1)/0.08 = (1.4693-1)/0.08 = 5.8666. Deposit: 50000/5.8666 = ₹8522.82 yearly. Check: 8522.82×5.8666 = 50000 ✓. Total deposits: ₹42614, interest earns rest! (Sinking fund: saving up!)