To stop Excel from dropping the initial zeros in a number, follow these steps:

1. Select the cells that contain the numbers with leading zeros.
2. Right-click on the selected cells and choose "Format Cells" from the context menu.
3. In the "Format Cells" dialog box, select the "Custom" category.
4. In the "Type" field, enter the following format code:
   Formula:

   000000 

   (replace the number of zeros with the maximum number of digits you expect to have in your numbers).
5. Click "OK" to apply the custom format to the selected cells.

By using this custom format, Excel will treat the numbers as text and will not drop the leading zeros. Even if you enter a number without leading zeros, Excel will automatically add them and display the full number with the correct number of digits.

Note that this custom format will only work for numbers with a fixed number of digits. If you have numbers with varying lengths, you may need to use a different format code or a formula to add the leading zeros.