Futility Closet

Bullseye

Posted in Science & Math by Greg Ross on October 27th, 2006

0.999… is the same as 1. Not just very close, but precisely identical:

a = 0.999…
10a = 9.999…
10a – a = 9.999… – 0.999…
9a = 9
a = 1

There’s no trick here. It’s just a mathematical fact that most people find deeply counterintuitive.