If I type in the following number into a field:
123,456,789,123,456,789
and hit enter, I get the following number in the field:
123,456,789,123,456,000

If I then take the second number, subtract 2 from it in another cell, and
then do an exact function on the 2nd and 3rd (now 2 less than the 2nd), I get
a "TRUE" result.

I'm using Excel 2003, service pack 2.