Yes it is. See the article about forcing a specific language and note the difference between culture which is used for date and number formating and uiculture which determines which resx (language) files are used for labels and buttons.
Note also that if you are doing ecommerce ie using webstore you would not want it to be up to the users preference because then prices may show in the wrong currency format.
But if you don't want to force a language and you do want it to adapt for some weird reason only numbers and dates then you would not force a language but just remove the auto: from the uiculture attribute on the gloabalization element in web.config
See also Localization
Hope that helps,