The NOW Function returns the current date and time − formatted as date and time − as shown below in cell B1. If the cell format was General before using the function, Excel will change the cell format to match your regional settings for date and time.
The NOW Function has no arguments, but the empty parentheses () is required, as seen in the formula bar above.
The NOW Function is Volatile, meaning every time Excel calculates the worksheet the function result changes. And you can’t always tell when this will happen. To see what I mean, enter a NOW Function in a worksheet cell then play around with the worksheet.
I’m not a big fan of Volatile functions. Used sparingly they can serve a specific purpose, but left unchecked in a workbook with a large amount of data they can drastically slow things down.
The cell formatting in cell B2 is General and you can see the serial number. The integer to the left of the decimal point represents the date, and the numbers to the right of the decimal point represent time.
The B3 cell format is Date and you see only the date portion. The B4 cell format is Time and you see only the time portion. Both cells have the same underlying value, 40409.47966.
Tip for Static Date or Time
To enter the current date into a worksheet use the keyboard shortcut Ctrl+; (semicolon). To enter the current time use Ctrl+Shift+: (colon). Both are static entries that won’t change.