Using Monday, Friday or Sunday dates to find relating month, If last week of a month has a Wednesday, then that week is part of same month

[atearth]

I'm currently trying to using Monday, Friday or Sunday dates to find relating month, to show week X is part of month Y.

	A	B	C	D
1	Week Commencing Monday	30-Jan-17	29-Jan-18	28-Jan-19
2	Week Ending Friday	03-Feb-17	02-Feb-18	01-Feb-19
3	Week Ending Sunday	05-Feb-17	04-Feb-18	03-Feb-19
4	Month	01-Feb-17	01-Jan-18	01-Jan-19

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B4 is 01-Feb-17 due to the week in question only having Monday & Tuesday in Jan-17. So the week in question would be part of Feb-17.

C4 and D4 would be 01-Jan due to both weeks in questions having Monday, Tuesday and Wednesday in Jan-YY.
Any ideas as to what formula to use?

Would leap day affect the formula used?

 

[James006]

Hello,

Not sure to fully understand your objective ...

Could the WeekNum() function applied to B1,C1,D1 be of any help ?