If you are working with a .xls or a .csv file with a number field that contains a lot of leading zeros, e.g. 0001234, you may find that the leading zeros are not importing correctly.
The first thing to consider is that leading zeros at this time will only be imported correctly to a plain text field, not a number field.
If the problem persists with a text field, the following are a series of steps that will help ensure that all zeros are published correctly.
How to prepare your data file with leading zeros for upload:
1) Save your .xls file as a .csv
2) Then open a blank Excel document
3) Click the "File" tab then click "Import"
4) Select "CSV file" click Import
5) Select the file you would like to import
6) Select "Delimited" and click Next
7) Click Next again
8) Click on the columns that you would like to retain the 0s, and click the option for "Text", NOT "General"
9) Click Finish and Okay