I mentioned in a previous post that Google has calculator abilities built in. Well, it seems they're wasting a lot of money on all those highly intelligent technical minds that they employ as it seems they can't get Google to do some simple maths correctly.
Go to the Google site and enter the following into the search box:
1 - 0.9 - 0.1 and hit enter or any of the buttons and check out the answer... erm, well yes... that looks about right. (Screenshot for the archives)