3. (8 points) As shown in the figure, four squares are placed inside a large rectangle with a length of 19 cm and a width of 11 cm. The area of the small rectangle (the shaded part in the figure) that is not covered by the squares is ______ square centimeters.
$\qquad$ 6
【Solution】Solution: The side length of the largest square is 11 cm,
The side length of the second largest square: $19-11=8$ (cm)
The side length of the smallest square is: $11-8=3$ (cm)
The length of the shaded rectangle is 3 cm,
The width is $8-3-3=2$ (cm)
$3 \times 2=6$ (square cm)
Answer: The area of the small rectangle not covered by the squares (the shaded part in the figure) is 6 square cm. Therefore, the answer is: 6.