One strawberry has 7 mg vitamin C, so women would need 11 strawberries to get a day's worth of vitamin C and men would need to eat 13. Eleven strawberries also have 42 calories and 21 mg calcium.
It would be easy to eat that amount of berries to get one day's worth of vitamin C, but you don't need to eat that much as long as you're getting other sources. Here's some nice way to get strawberries into your diet:
United States Department of Agriculture National Nutrient Database for Standard Reference. "Strawberries, raw." Accessed October 22, 2010. http://www.nal.usda.gov/fnic/foodcomp/search//.