recently sent me some links; the first is by Albert A Bartlett.

Bartlett is a mathematician, and has been described as a ‘neo

malthusian’. You may not like his conclusions, but his arithmetic is

undeniable.

For anyone who thinks videos about arithmetic probably won’t be as fascinating as ‘Star Wars’ the important thing to take away from this vid comes very early: Growth and doubling time. In summary, if you see a percentage growth quoted, divide it into 70 to find the doubling time.

IOW, if you see growth (of say population) of 7%, divide that into 70 to arrive at a doubling time of 10 years.

If you want to know the Why and How, watch the vid.