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.

Launch Microsoft Excel 2010 and open the spreadsheet you want to edit. Select the worksheet for which you want to insert the page number. Click the "View" tab on the upper side of the Excel window.

For example, to add the numbers 10, 20, and 30, click the desired cell, then type the formula below and hit Enter. =10+20+30 The result (60) will appear in the selected cell.

By default, it allows you to insert only text header and footer. However, let’s assume that you want to insert the page number, number of pages, current date, current time, etc.

You can use SUMIF in Google Sheets to add numbers together that are associated with a date range, specific text, or meet a numeric criterion.