Perimeter of a square is the sum of all four sides. Since all the sides have same measure (say "a"), hence perimeter is given by:
Example 1: Find the area and perimeter of the square whose side length is 8 meters.
$a = 8m$
Area of square = $a^2 = 8 \times 8 = 64 m^2$
Perimeter of the square = $8 \times 8 = 64 m$
Example 2: Each side of a square is 6.5 cm. Find its perimeter.
Solution: Side = $6.5 cm$
Therefore, perimeter of a square = $4 \times length \ of \ a \ side$
= $(4 \times 6.5) cm$
= $26 cm$