To know the rate of return every year of a double-your-money proposition, simply ask the question: Over what time does my money double? Then divide 72 by that number. Suppose the agent says: Your Rs 1 lakh will grow to Rs 2 lakhs in fifteen years, divide 72 by 15. Your return per year is 4.8 per cent, which is near the 4.73 number that a more exact calculation will give.
