In this case,we have to use
=SUMPRODUCT(1/COUNTIF(SELECT RANGE,CRITERIA))
Note:-
HERE,
Range and Criteria are same,hence Formula actually is
=SUMPRODUCT(1/COUNTIF(SELECT RANGE,SELECT RANGE))
EXAMPLE
  
 
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View AnswerFor Question 1: To Calculate how many subjects.
  We can make a pivot table and count the subjects.
  
  or 
 
  We can use countif and sumproduct formula
  
   
  
-ea-
