A cylinder is a hollow surface and has two circles-one on top, one at the bottom; and a rectangle in the center. The formula of volume of a cylinder is area of the base circle multiplied by the height of the cylinder or the rectangle. Area of a circle is pi multiplied by square of the radius. Therefore, to find the volume of a cylinder, the first step is to find the height. Step two is to find the radius of base of cylinder. In a circle, a radius is the distance from a point on the circle to its center. It can also be found out by dividing the diameter by two or into half.

The third step is multiplication of pi with the square of the radius and with the height. The value of pi is 3.14. The square of radius is multiplying radius with itself that is, multiplying radius two times. The final step is to write the answer. Let v be the volume of the cylinder, r be the radius of the circle and h be the height of the cylinder. Then, v = pi x r2 x h, same units should be taken for each dimension. If we take the radius in centimeters, take the height too in centimeters.

For example, take h = 20 cm, r = 4 cm.
Then, volume, v = pi x r2 x h
Pi = 3.14.
Thus, v = 3.14 x 4 x 4 x20 = 1004.8 cm3