Originally posted by Bodak
We can "doctor" 0.9r to "add" 9's.
Edit - for anyone who things 0.9r=!1, of course. For others, you prob. know this by heart.
The Gauss formula, for the nth time...
a / (1-r) is the "sum to infinity" of a geometric progression, where...
a is the first term
1 is 1.
r is the common ration, which is the ratio of any two consecutive terms.
Consider 0.9999r to be...
0.9 + 0.09 + 0.009 + 0.0009 +.....
a is 0.9
1 is 1
r is 0.1
0.9 / (1-0.1) = 0.9 / 0.9 = 1.
The series converges to 1. Therefore, 0.9r = 1