I have seen the formula
=IF(SUMPRODUCT(($A$2:$A2=A2)*($B$2:$B2=B2))>1,0,1) in here
I am confused about this equal sign
= … What is it for ?
It is used for comparison.
If the range
$A$2:$A2 is equal to
A2, then it evaluates to
It’s similar if you type in a cell
=2=2, you’ll get
TRUE as result, except the one in your question is comparing a range with a single cell.
Anchoring the top row of the range with $A$2 but allowing it to expand by not anching the row in the second cell reference allows to to have one instance where the sumproduct() will return only one value. If the full range was included in all cells, any value that occurred two or more times would have a 0 value returned.