How much data have I used on my iPhone? - 1

I currently have AT&T, and when I type *DATA#, it says I have used 108.55 of 1024. Does that mean I've used 108%(so I went over?) or does it mean I've used about 10% of 1024. It makes a big difference and I'm confused

Assuming that is the usage and not what is left it means you have 1024mb of data to use ( one gig ) and have used 108.55 mb
1024mb is on gigabyte

No. That means what it says, you've used 108.55MB of 1024MB meaning 10.6%