So, a million years ago, I was the first programmer hired in the NYC offices of Montgomery Securities (long since acquired.) to build trading systems or some su

So, a million years ago, I was the first programmer hired in the NYC offices of Montgomery Securities (long since acquired.) to build trading systems or some such. I was sitting up with the analysts in the cherrywood cube farms late one evening when one day I heard, "Biff, the rule of 72 doesn't really work?" "what do you mean, Chet?" "well, if you get 72 percent return, you don't double your money in one year!" Then they poked at it with an excel model for like 30 minutes. I eventually had to tell them that you can't precisely model compound interest (an exponential equation) with a linear model. "whoa... Why are you in IT?!?" Ah, those were the days.