Hi there, welcome to FitDay!
If you subtract the second number from the first number, it gives you the third number. What this is saying, essentially, is that the second number is how much of a calorie deficit you have to have in order to lose what you want to lose in the time period you specified when you set your goal. So no, you don't need to burn 657 more.
According to the math, in theory, you can eat that much and still lose, because you are burning more than you eat. However, you will probably have better success if you eat fewer calories than that. Try some different calories counts and see what is best for you in terms of keeping you not too hungry but also enabling you to lose at a fairly steady rate.
Please feel free to jump into any of the forums and get to know us. If you have any other questions, just holler!
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days