Hi, I have spent countless days trying to find a formula that will allow me to find duplicates across Multiple Sheets within a single workbook. All resources I have checked only allow duplicate finding formulas for a single Sheet. I have multiple sheets 1 to 31 representing a month in which I have a column of phone numbers. i want to be able to know from sheet to sheet (Day to Day) if I may be retyping a number from a previous day. Thatís why I need to have a formula to check across the sheets for duplicate numbers. Even better if I can have the duplicates displayed on a new sheet. Any formula or help would be much appreciated. Thanks In Advance.