How do I change the format to allow a zero as a first digit?

[MongoTom]

When I input an ID number, they all start with a zero. Excell automatically
removes it. How do I turn off this function?

 

[T. Valko]

One way is to enter the number as a TEXT entry. To do that precede the entry
with an apostrophe like this: '012345. The apostrophe will not be visible in
the cell.

 

[Max]

Either precede your entry with an apostrophe, or pre-format the col as TEXT

 

[Bigfoot17]

I do this regulalry as I have position numbers which are 5 digits. Format the
cell(s) with Format/Cells then category="Custom" and type=000000. This way
if you enter 16 it will display as 000016. My only caution is that is you
search for 000016 you will not find this cell, you would need to search for
16.