Credit card companies win big by charging this type of compound interest, and if you're not paying attention, your debt can grow at an alarming rate. This is where the rule of 72 comes in.

The 'rule of 72' is a secret weapon to help keep credit card payments from spiraling out of control - and the beauty of it lies in how easy it is to apply. In short, if you divide 72 by the ...

The number of years which will take to double the credit card obligation will be 72/24 = 3 (years) as per the rule of 72. In other words, it will take three years for the credit card debt to double.