Thank you taking the time to help!

I am importing and concatenating long text strings from multiple sources. These are actually numeric data but Excel's limit of 16 numeric characters prevents me from saving them as such. One of the strings that I 'tie' into a longer text value is a ten digit 'number'. This number frequently includes leading zeros but on the source formatted document (not Excel) these zeros are often 'stripped' before the data can be imported to Excel. My goal is to append any imported values less than ten digits in length to 'fill' with leading zeros.

Desired Value (in text format):
0123456789

Currently imported value (in text format)
123456789

Is there a function within Excel to do this neatly and conveniently?

Thank you