I'm taking this one from Graham's book. 72 / 12.57 ~= 5.73 72 / 13.96 ~= 5.16 72 / 8 = 9 These are rule of thumbs on how many years it'll take for your mone

I'm taking this one from Graham's book. 72 / 12.57 ~= 5.73 72 / 13.96 ~= 5.16 72 / 8 = 9 These are rule of thumbs on how many years it'll take for your money to double if you have that rate consistently. So on a 40 year time horizon, one would get: 40 / 5.73 ~= 7 doubles 40 / 5.16 ~= 7.75 doubles Still way better than 4.44 doubles with 40/9 Hypothetical balances of 10K would be: 10000 * 2^7 = 1,280,000 10000 * 2^7.75 = 2,152,695 10000 * 2^4.44 = 217,056.7 Compound interest is one hell of a drug ;-)