The ceiling of Katie’s living room is a square that is 20 ft long on each side. To decorate for a party, she plans to hang crepe paper around the perimeter of the ceiling and then from each corner to the opposite corner. Katie can buy rolls that each contain 8 ft of crepe paper. What is the minimum number of rolls she should buy? Show your work.

The room is a square, meaning all four sides are 20ft long.

Because we know all the side lengths, we can find the perimeter of the square by adding the side lengths together.

(20 + 20 + 20 + 20)  = 80

Now that we know the perimeter, we have to match this number to the feet of crepe paper.

We can find this by dividing the total length needed by the length a single roll provides.

80 / 8 = 10

Therefore, we know that Katie will have to buy a minimum of 10 rolls if she wants to cover the entire perimeter of the room.

Hope this helps! :)