COUNTIFS
Category: Statistical Function.
Description: Returns the number of entries that satisfy all specified criteria in specified ranges.
Syntax: COUNTIFS( criteria_range1, criteria1, [criteria_range2, criteria2], ... )
Each additional range must have the same number of rows and columns as the 'criteria_range1' argument.
The ranges do not have to be adjacent to each other.
Criteria is applied to the associated range and the logical matrix (true/false) is calculated.
Resulting matrices are added using the AND operator, and the number of True entries is counted.