Any users of Microsoft's spreadsheet app that deal with datasets that include phone numbers will at some point have run into a problem in which Excel treats a phone number as a "real" number and therefore removes the first zero. Here's our guide on how to prevent this.
Method 1a: Microsoft Excel is primilarily a tool for applying analysis and formulae to numbers, so its default is to treat everything as a number. A number cannot start with a zero (decimal points aside), so if you enter one, it removes it. This poses a problem when adding phone numbers, which (depending on the phone number format) often start with a zero.
Here is a very simple spreadsheet that includes a phone number column. What we need to do is tell Excel not to treat this as a number, but as text, and therefore not to apply any processing to it. If you have (or intend to have) a whole column of phone numbers, right click the phone column and select "Format Cells"
Method 1b: In the screen that appears, pick "Text" from the category menu and click OK. This will then ensure any phone number entered into that column will be treated as text and therefore it will just show the data exactly as entered.
Method 2: The other way to tell Excel to treat data as text is to enter an apostrophe (') before that data. So in this case, the phone number would be added as '07700123456. This would then display without the apostrophe in Excel once you move to the next cell, and Excel won't take any action to "fix" what you've entered.