You want to wallpaper a room. Your room is 10 feet by 12 feet and the ceiling height is 10 feet. A double roll of wallpaper covers approximately 56 square feet of wall. How many double rolls of wallpaper should you buy?
What you need to calculate is surface area of the room. SA = 12 * 10 * 2 (for the two 12 ft long walls) = 240 ft^2 SA = 10 * 10 * 2 (for the two 10 ft long walls = 200 ft^2 200 + 240 = 440 total square feet of wall space. Each double roll covers 56 sq ft. 440/56 = 7.86 double rolls; you cannot buy a partial double roll so we need to buy 8 double rolls
