it depends how long the width and the length is. If the length is 5 cm and the width is 4 cm the perimeter will be 18cm. All you have to do is 5 doubled because there 2 sides for the length and 4 doubled because there are 2 sides for the width. I hope I have answered your question. XD
My answer was wrong, please delete this
It is just 5.0 and you move the decimal right six places
