New Delhi, Feb. 25 -- The rule of 72 tells you how long it takes to double the money at the current interest rate. This is quite a valuable and insightful metric which tells you the time period during which you can increase your investment by 100 percent. Importantly, this also tells you the tenure during which yourcredit card debt can increase by 100 percent of the original debt.

For instance, if the credit card's APR (annual percentage rate) is 24 per cent based on 2 percent monthly interest which the bank is charging. The number of years which will take to double the credit card obligation will be 72/24 = 3 (years) as per therule of 72.

In other words, it will take three years for the credit card debt to double.

If you, too, are wor...