I just noticed that Excel 2000
makes a mistake when calculating weeknumbers in 2005.
Could that be an Excel-bug?

23-12-2004 52 =WEEKNUM(C4;2) OK
24-12-2004 52 OK
25-12-2004 52 OK
26-12-2004 52 OK
27-12-2004 53 OK
28-12-2004 53 OK
29-12-2004 53 OK
30-12-2004 53 OK
31-12-2004 53 OK
01-01-2005 1 WRONG Should be 53
02-01-2005 1 WRONG Should be 53
03-01-2005 2 WRONG Should be 1
04-01-2005 2 WRONG Should be 1
05-01-2005 2 WRONG Should be 1
06-01-2005 2 WRONG Should be 1
07-01-2005 2 WRONG Should be 1
08-01-2005 2 WRONG Should be 1
09-01-2005 2 WRONG Should be 1
10-01-2005 3 WRONG Should be 2
11-01-2005 3 WRONG Should be 2

Best regards,
Arien de Haan
Eindhoven NL