adding digits in a column

Hi, I have a csv file with country codes in a column , I need to add 011 infront of each code ,how can I do that?For example for country code USA there is 1 I need to make it 0111 , I need to do the same for all country codes.

Telephone numbers are not numbers! Number is something that is used for calculations. Addition, subtraction, taking average, … Telephone numbers are a kind of codes, which need to be handled verbatim. Always use text fields for such things!

thanks mike I appreciate your reply , I could add required digits by changing format to text ,but how to add to all cells in the column?