The lily pond
A water lily patch doubles in size every day. On day 30 it covers the whole pond.
On which day was just a QUARTER of the pond covered?
Where these numbers come from
This is a thought experiment, not a real plant: the classic lily-pond riddle used to explain exponential growth.
The Limits to Growth (1972), ch. 1 — Club of Rome / Universe Books(checked 2026-09-26)