“There is a law called Rule 72 (72 divided by interest equals the number of years to double investment) which most people have never been taught. It’s also unfortunate that in America you can receive an elementary, high school and college education and never be taught Rule 72. If you earn 1% on your money, it will take 72 years for $1.00 to become $2.00.

Rule 72:
1%= 72 years
4%= 18 years
5%= 14.4 years
6%= 12 years
10%= 7.2 years
12%= 6 years
18%= 4 years
24%= 3 years

At a 12% return, $10,000 becomes:
$20,000 in 6 years
$40,000 in 12 years
$80,000 in 18 years
$160,000 in 24 years
$320,000 in 30 years
$640,000 in 36 years.” -From, “Black Economics: Solutions for Economic and Community Empowerment” By: Jawanza Kunjufu