What is 1 over 0 as a decimal?

1 divided by 0 is infinity. So you can't really write it as a decimal.

It is not technically possible to divide something by 0. Seriously, try entering it into a calculator. I know for a fact that on mine it has a special 'divide by zero' error.

Yes, I was a bit hasty saying it was infinity. In fact mathematicians say

a number divided by zero is "undefined". As you divide 1 by smaller and smaller numbers the result "tends to infinity" as the "limit".