Why does date change when copying to new sheet?

[Guest]

My list of dates is changing when I copy sheet from original workbook to new
workbook. For ex, 02/06/2006 changed to 02/07/2010. How can I fix this?

 

[Niek Otten]

There are two date systems in Excel: the "normal" system (default in Windows
systems) and the "1904-system". The latter is used on Mac systems.
On a Windows system: check your date system in Tools>Options>Calculation.

 

[Dave Peterson]

Just to add to Niek's response...

One workbook was using a base year of 1900 and the other was using 1904.
(tools|options|calculation tab|1904 date system)

One way to add those four years back is to find an empty cell, put 1462 into
that cell.

Copy that cell.

Select your range that contains the dates. Edit|PasteSpecial|click Add (in the
operation box).

You may have to reformat the cell as a date (mine turned to a 5 digit number).
But it should work.

You may want to do it against a copy...just in case.

(I'm not sure which one you'll fix. You may want to edit|pastespecial|click
subtract.)

Most windows users use 1900 as the base date. Mac users (mostly??) use 1904 as
the base date.

 

[Guest]

I thought I had read this before and checked to make sure. According to John
Walkenbach, you cannot change the date system if you use Excel for Macintosh
and Excel for Macintosh uses the 1904 date system.