One way:

=TEXT(code1,"000000\/") & TEXT(code2,"0000")

In article ,
Orion wrote:

Hello everybody,

I have a table with codes (6digits). Some of them start with a zero.
I formatted the cell with a custom format: 000000, which works fine.
Instead of 41719, I can see 041719

In a certain cell I concatenate the entries of two cells, the above
mentioned code and another code.

=concatenate(code1," / ",code2)

637002 9588 becomes 637002 / 9588

but

041719 9580 becomes 41719 / 9580

I lost the zero in front and I have no idea how I can get it back. I
tried various possibilities with cell formats.

The idea of formatting the code1 table as text and write '041719, I
don't like, because in case of sorting the table, these entries will
be at the end instead at the top.

Thanks,
Norbert