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Hi, I encountered a problem that might need a bug fix in Excel. When the WEEKDAY function gets its input from a blank cell or is 0 (zero), the result is Saturday. The formula was written =WEEKDAY(0), the result is 7. Shouldn't it provide #NUM! as a result? For me it created trouble in array entered formula used to calculate conditional averages.
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Answer accepted by question author
Hi,
0 corresponds to a date 0 January 1900. This is probably 31 December 1899. Apparently, that was a Saturday.