See how to:
(00:51) Count Columns with COLUMNS Function
(01:08) Count Rows with ROWS function
(01:30) Count Unique Numbers using FREQUENCY and SUM Functions
(04:41) Create Data Validation Drop Down List of Unique Items in the Two-Way Lookup Table.
(05:29) Create Array Formula to look up Column Headers. See the Functions: INDEX, SUMPRODUCT and COLUMN.
(09:44) Create Array Formula to look up Row Headers. See the Functions: INDEX, SUMPRODUCT and ROW.