Three colleagues split a taxi fare of ₹25. Each hands over ₹10 (₹30). The driver realizes the fare should be ₹25 and gives ₹5 to his assistant to return. The assistant gives each colleague ₹1 and pockets ₹2. Now each colleague has effectively paid ₹9 (3×₹9 = ₹27) and the assistant has ₹2 — that makes ₹29. Where did the missing ₹1 go?