If start date is 1/1/17 formula is
=LARGE((SUMIF(OFFSET($B$2,0,ROW($1:$180)-ROW($1:$1),1,30),">0")/30),1)
ARRAY formula is used
To enter ARRAY formula
Paste the formula
Press F2
Press Ctrl+Shift+Enter keys together.
formula will be covered with{} brackets by excel.
|