From the figure, it can be observed that the side of the square is 42 cm.

Area of square = (Side)^{2} = (42)^{2} = 1764 cm^{2}

Area of each circle = π r^{2}

^{ }= 22/7 x 7 x 7 = 154 cm^{2}

Area of 9 circles = 9 x 154 = 1386 cm^{2}

Area of the remaining portion of the handkerchief = 1764 − 1386 = 378 cm^{2}