When you begin to use your calendar in Outlook, the week numbering is inactivated. If you want to activate it, you go to calendar options for Outlook.

1. Click on the tab Outlook, in the upper menu bar.
2. Choose Preferences.
   
   
3. Click on Calendar under ”other”
   
4. Under Calendar options you mark the box for Show week numbers.
   
   
5. You now have week numbers in your calendar in Outlook.