Format the cells as Text before entering the data
Type an apostrophe before the number, such as ‘00123
Use a custom number format with the required number of digits, such as 00000
Import data using the Text Import Wizard and set the column format to Text
Use the TEXT function, such as =TEXT(A1,”00000″)
Store the values in a text-based source before pasting into Excel
Avoid using General format for values that need leading zeros