How much data have i used on my iphone?

It says i sent 13.6 MB and received 84.8 MB. I scared i'm going to go over, i know i'm nowhere close but thats what i used in a day. I have 2 GB a month. Can someone explain it to me?

1gb = 1000mb (approx, that's what the phone companies use)

You've used 100mb that day, you could do the same thing for 19 more days in a month (2000mb / 100mb = 20 days total) to hit your limit. If you have Wi-Fi at home, switch to that to save data. Otherwise, remove some apps you don't use, change your habits (don't do quite as much per day), or get a bigger data package.

All carriers (AFAIK) have a way to check your data plan details and such, like dialing #PAY or #BAL or #MIN or just calling 611. Android has data usage tracking built into the OS where you can see how much data you've used for the day / month / etc.