If all sides of the square are even, you would multiply 17 by 4, 4 representing the 4 sides of the square 17x4=68 Then at the end write your unit of measurement
If a shape is a square, this mean that each side has the same length. This means that each side of the square has a length of 17cm. Perimeter is the length of the outer boundary of a shape or the summation (addition) of all the sides. This means that the perimeter of this square is 17+17+17+17 or 17×4 which is equal to 68cm. I hope this helps!
