There are a variety of modern definitions of economics, some reflect evolving views of the subject or different views among economists.
So the area of the square is 7 x7 = 49 cm^2 and the perimeter of the square is 7 x 4 = 28 cm. And in example 1 you have a square of side length 8cm and you need to work out the area and perimeter of the square. So the area of the square is 8 x8 = 64 cm^2 and the perimeter of the square is 8 x 4 = 32 cm.
In the International System of Units (SI), the standard unit of area is the square metre (written as m2), which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the same area as three such squares. In mathematics, the unit square is defined to have area one, and the area of any other shape or surface is a dimensionless real number. There are several well-known formulas for the areas of simple shapes such as triangles, rectangles, and circles.