How many square feet of carpeting are needed to carpet a 12-foot by 12-foot room

Square feet refers to area, so you would need to find the area of the room.

Area of a rectangle = length × width
Length = 12 ft
Width = 12 ft
A = l×w
= 12 ft × 12 ft
= 144 sq. ft

Thus, you would need 144 square feet of carpeting.