Determine the greatest number of figures congruent to \square_{\text {that can }} be placed in a 9 \times 9 grid (without overlapping), such that each figure covers exactly 4 unit squares.
Determine the greatest number of figures congruent to \square_{\text {that can }} be placed in a 9 \times 9 grid (without overlapping), such that each figure covers exactly 4 unit squares.