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.

How do you allow zeros in front of numbers in Excel? There are different methods to keep the leading zeros in a number in an Excel workbook.

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.