Question

Prove algebraically that 8.99999... = 9

Answer 1

1/9 = 0.111...
9/9 = 0.999... but also 1 because 9 divided by 9 is 1. Add 8 to both sided to get 8.9999... and 9

Answer 2

You can't, it has been done before but there is a fault in the working because the 2 numbers are different. If you want to see a video of someone attempt it, I believe there is a video on the numberphile channel.

Hope this helps :)