the cell format is set for numbers as a Date.
the following will correct the trouble.
select the cell
right click and select Format Cells
on the Number tab page select Number from the list
click OK.
The number should then show the original value that was entered.

I think this will work on entire columns as well but I haven't used it in a
while.

HTH
scruffy

"km" wrote:

How do I stop excel from changing/calculating the numbers typed in to a
specific column I can't find any indication it is calculating but it changes
the 9 digit ID number into a date format with different numbers ?