To enter the current date and time in a cell:
     Type =Now()
 

To enter the current date only:
     Type =Today()

The above option will change each time you open your spreadsheet but use the following procedures to control these options.

To insert a fixed date in a cell:
     Press and hold the Ctrl (Control) key and press the semicolon (;) key

To insert a fixed time in a cell:
     Press and hold the Ctrl (Control) key, Shift key and press the semicolon (;) key