A sphere is a three-dimensional, round object, such as a marble or soccer ball. The volume represents the space enclosed by the object. The formula for the volume of a sphere is 4/3 times pi times the radius cubed. Cubing a number means multiplying it by itself three times, in this case, the radius times the radius times the radius. To find the volume in terms of pi, leave pi in the formula rather than converting it to 3.14.

Multiply the radius times the radius. For example, if the radius of your sphere equals 19 inches, multiply 19 by 19 to get 361 square inches.

Multiply the result by the radius. In this example, multiply 361 square inches by 19 inches to get 6,859 cubic inches.

Multiply the result by 4. In this example, multiply 6,859 cubic inches by 4 to get 27,436 cubic inches.

Divide the result by 3. In this example, divide 27,436 by 3 to get 9,145.33 cubic inches.

Multiply the result by pi to find the volume of the sphere in terms of pi. In this example, multiply 9,145.33 by pi to find the volume equals 9,145.33*pi.