# Independent answer check

The unique nonblank names are North Pier, Cedar Lab, Harbor Co, and Ridge Works: four customers. The source range A2:A9 has eight rows, six nonblank entries, and two blank rows. North Pier and Cedar Lab repeat; neither repeat adds to the distinct count. The formula =ROWS(UNIQUE(FILTER(A2:A9,A2:A9<>""))) returns 4 in supported modern Excel.

Independent set calculation over nonempty strings: {North Pier, Cedar Lab, Harbor Co, Ridge Works}, cardinality 4. Six nonblank source entries and two blanks reconcile to eight rows.