The problem did not state if the 1cm measure is the radius or diameter.
Area of a circle = π r²
Assuming: 1 cm is the radius
Area of 1 button = 3.14 (1cm)² = 3.14cm²
Total area = 3.14cm² 7 buttons = 21.98 cm²
Assuming: 1cm is the diameter : radius is 1/2 = 0.50cm
Area of 1 button = 3.14 (1/2cm)² = 3.14 0.25cm² = 0.785cm²
Total area = 0.785cm² * 7 buttons = 5.495cm²
