excel - COUNTIF date occurs in same week number and year

Question

I have a bunch of dates in Column C, and then other dates in column J. How would I count the instances of dates in column C that fall in the same week number (and same year) as a date in a particular cell in column J?

Thanks for all help in advance

Answer 1

Something like

=SUMPRODUCT(--(ISOWEEKNUM(J1)=ISOWEEKNUM($C$1:$C$10)),--(YEAR(J1)=YEAR($C$1:$C$10)))

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Data