What is the number of carbs you should eat a day?
It depends on your body weight, your life style and your metabolism (how much calories you body burns to function)
I have An app that says my daily calorie intake should be %55 Carb ,%30 Fat, % 15 Protein...and I've lost 16-17 lbs in about a month and a half from this app..MyFittness Pal
The number of carbs that you should eat in a day would be, the amount of calories you take in a day divided by 4. Everybody requires different carbs in a day, it all depend on the amount of calories you take. Learn how to calculate right from http://nutrition.about.com/od/askyournutritionist/f/howmanycarbs.htm.