When you type a seven-or-ten-digit phone number into an Excel cell that uses the phone number format, Excel will automatically change the way the number looks so that it appears as a phone number.

You can add a zero before a number in Google Sheets and Excel using this tutorial. You need to change cell formatting or use function.

Excel considers dates and times as numbers in cells, making calculation difficult. Excel processes 6 AM as "0.25," because it is one quarter of the way through the day. If you need to add a number ...