Shruti Speak's

Rule of   "72 "      If you divide the  number 72 by the rate of interest, you get to know the  number of years it will take for you to double the money 72:   is sort of a magic number of personal finance, a.k.a known   as the rule of 72 in  personal finance parlance. All you   need to do is a quick calculation (mentally if you know   fifth grade math tables) and you can verify, if the cheeky   agent is giving you hogwash.     *Years:* If   you divide the number 72 by the rate of interest, you get to  know the number of years it will take for you to double the  > money. For instance, if the rate of interest is 9%, simply   divide the number 72 by 9% and the answer is eight. This is   the number of years it will take to double your money if you   invest it at 9% rate of interest.     *Interest:**...