"Craig" wrote in message
. ..
Is there a simple way to calculated the number of months between two
dates?

http://www.cpearson.com/excel/datedif.htm

Also is there a way to change the default date display format from a four
year to a two year format (7/10/2006 to 7/10/06) so that all my entries
will always show the two year format?

Not Excel, but a Windows function, I think. Try Regional Options/ Short
Date.
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David Biddulph