Excel hasn’t been around for 40,000 days, but Excel’s date system starts at January 1, 1900 (day 1), and today is day 40,000. Not for Mac users though – its default date system starts at January 1, 1904 (day 0), so you won’t hit this milestone for another four years.
The two dating systems are explained in the Microsoft Knowledgebase article: Description of the differences between the 1900 date system and the 1904 date system in Excel.
Switch to a Different Date System
Whether you’re using Excel on a Windows machine or on a Mac, you can switch from the default date system. Follow these steps to switch to the 1904 Date System in Excel 2007:
- Click the Office Button, then click Excel Options
- Click the Advanced category
- Scroll down to the section titled, When calculating this workbook
- Add a check mark to Use 1904 date system.
- Click OK
Keyboard Shortcuts for Dates
If you use these shortcuts, you’ll have more time available for celebrating the 40,000 day milestone.
- Enter today’s date: Ctrl + ;
- Format a date as dd-mmm-yy: Ctrl + #