Description: Learn how to find the volume of a rectangular prism that has fractional side lengths. The prism in this video has dimensions 3/5 by 1 1/6 by 3/7. Created by Sal Khan. Let's see if we can calculate the volume of this rectangular prism, or I guess you think this thing is the shape of a brick or a fish tank right over here. One way to think about it is you're trying to pack unit cubes in here, and one way to think about how many unit cubes could fit in here is to think about the area of this base right over here. So sometimes you'll see volume is equal to the area of the base times the height.*Teacher Advisor is 100% free.