Solution:
9 = Number of circular designs
7 cm = Radius of the circular design
One side of a square handkerchief has three circles.
The side of the square = 3×diameter of circle = 3×14 = 42 cm
Squares’ area = 42×42 cm2 = 1764 cm2
The circles’ area = π r2 = (22/7)×7×7 = 154 cm2
Designs total area = 9×154 = 1386 cm2
Area of the square – Total area of the design = Area of the remaining portion of the handkerchief =1764 – 1386 = 378 cm2