A pyramid with a rectangular base has five faces. Since pyramids can have bases with any number of sides, the formula to calculate the number of faces is the number of sides of the shape that forms the base of the pyramid plus one.

Pyramids are three-dimensional figures with a polygon base and triangles that meet at one vertex. The vertex where the sides meet is referred to as the apex. The name of the pyramid is dictated by the shape at the base of the pyramid. A pyramid with a four-sided base is referred to as a square pyramid. The famous pyramids in Egypt are square pyramids.