The area of a circle with a diameter of 240 mm is: 45,240 mm2
The area of a circle whose diameter is 6 mm is: 28.27 mm2
A circle with a radius of 50 mm has an area of 7853.98 square mm
Diameter of a circle is pi times the square of its radius. For a circle having a diameter of 7 mm, area = pi (3.1416) x 3.5 mm x 3.5 mm = 38.5 square millimeters.
I do not know about a circle with an area of 100 nmm3.A circle with an area of 100 mm2 has a diameter of 11.28 mm.
A circle with a diameter of 25 mm has an area of 490.9 square mm.
Area = pi*282 square mm
Area = pi*552 square mm
Area in square mm = pi*1252
A circle with a diameter of 4 mm has an area of : 12.57 mm2
Area = 136.85 mm2
Using 3.14 as Pi the area of circle is: 226.865