Doubling

Riddle: A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

Answer: Nine Years.

Source: https://www.riddles.com/index.php/273

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height? — Doubling by Anonymous v1.

Riddle: A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height? Answer: Nine Years. — by Anonymous v2.