Arithmetic Grade Four

Lesson One hundred and sixty-nine: Perimeter

Here's another rectangle for you to take a look at.

As you can see it has a height of 5 units and a length of 24 units. To find the total distance around this object you simply add up the length of each side. 


   PERIMETER = 5 + 5 + 24 + 24 = 58 units

   Alternatively you could use multiplication as a slight short cut:

   PERIMETER = 5 x 2 + 24 x 2 = 58 units

    OR

   PERIMETER = (5 + 24) x 2 = 58 units
Remember units can be inches, feet, yards, meters, or any other unit of length. We use the term units when the actual unit is left unspecified.

If you happen to get a square then finding the perimeter is even easier:

Since all four sides are equal you can just multiply: 


      4 x 7 = 28 units
Of course you could find perimeters for pentagons, octagons, or any other shape. In any case you just add up the length of all the sides and you have the perimeter of the object.

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