To turn ₹5 lakhs into ₹15 lakhs, you must first invest ₹5,00,000 in a Post Office Fixed Deposit for 5 years. The Post Office gives 7.5 percent interest on a 5-year fixed deposit. According to the current interest rate, the maturity amount after 5 years will be ₹7,24,974. Fix this money again for 5 years without withdrawing it. If you do this, you will get ₹5,51,175 through interest on ₹5 lakhs in 10 years. Then your total will be ₹10,51,175. This is more than double.