The following is a mathematical proof that 1 is equal to 0.999.... What's wrong with it? Click below for the answer.

$x = 0.999...$

$10x = 9.999...$

$10x = 9 + 0.999...$

$10x = 9 + x$

$9x = 9$

$x = 1$

$10x = 9.999...$

$10x = 9 + 0.999...$

$10x = 9 + x$

$9x = 9$

$x = 1$