Slide 4 of 37
Notes:
If you accumulate compound interest at 1% per year on a debt, it takes 70 years for the sum you owe to double.
If the rate is 2% per year, the doubling time is 70 / 2 = 35 years.
If the rate is 4% per year , the doubling time is 70/4 = 17.5 years, etc.
The same arithmetic holds for population growth:
4% growth /year implies a doubling every 17 years!