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.
Area of a square = side times side. Since each side of a square is the same, it can simply be the length of one side squared. If a square has one side of 4 inches, the area would be 4 inches times 4 inches, or 16 square inches. Be sure to use the same units for all measurements. You cannot multiply feet times inches, it doesn't make a square measurement.