Understanding Rectangular Prisms: Help for Math Students
In middle school, you'll learn formulas for finding the surface area and volume of rectangular prisms. Keep reading for a complete introduction to this important geometry skill!
Help with Rectangular Prisms
A rectangular prism is a solid, 3dimensional object with three sets of parallel sides that are at right angles to one another. Bricks and packs of playing cards are rectangular prisms.
Surface Area
Surface area is the amount of 2dimensional space that the surface of an object occupies. It's calculated by adding the areas of each of an object's surfaces. A rectangular prism has a total of six surfaces (sides), and they are all rectangular. You can find the area of a rectangle by multiplying its length and width (A = L x W).
To find the surface area of a rectangular prism, find the area of each of its sides and add them together. Or, since there are three pairs of identical sides, you can find the area of one of each of these sides. Then, multiply each area by two and add the results together. Here's an example of how to find surface area with a rectangular prism that's ten centimeters high, five centimeters wide and three centimeters long:
Surface area = 2LW + 2LH + 2HW
= 2(3)(5) + 2(3)(10) + 2(10)(5)
= 30 + 60 + 100
= 190 centimeters squared
Volume
The volume of a 3dimensional object is found by multiplying the area of its base by its height (V = b x h). Since rectangular prisms always have rectangular bases, the area of the base is the product of its length and width (L x W). This, multiplied by the rectangular prism's height, produces the formula L x W x H. Here's an example of how to find the volume of a rectangular prism with a length of six inches, a width of nine inches and a height of two inches:
Volume = L x W x H
= 6 x 9 x 2
= 108 cubic inches
Units
Some geometry problems state the dimensions of objects in different types of units. For instance, you might be asked to find the volume of a rectangular prism with a length of one meter, a width of 15 centimeters and a height of 12 centimeters.
Since the length of one side is given in meters, while the lengths of the other two sides are given in centimeters, you'll need to convert the lengths so they're all in a single type of unit. In this case, it would be simplest to convert the length of one meter to 100 centimeters, and then solve the problem. Sometimes, problems will specify which unit you should report your answer in, which is a clue that the dimensions of the sides are not given in like units.
It's also important to give your answer in a unit appropriate to the type of measurement in the problem. Remember that line segments are measured using units like inches and centimeters, while areas are measured in square units, such as square inches and square centimeters. The volume of a solid is always given in cubic units, like cubic inches or cubic centimeters.
Other Articles You May Be Interested In

Could you use a few tips on making reading to your preschooler not only enjoyable for you, but for them as well? This article tells you how to go about doing just that. Read on for the second installment in the series of articles on making the most of reading to or with your children.

Music can help improve a toddler's intelligence, brain function, and general quality of life. Read on for more information on exposing your toddler to music.
We Found 7 Tutors You Might Be Interested In
Huntington Learning
 What Huntington Learning offers:
 Online and incenter tutoring
 One on one tutoring
 Every Huntington tutor is certified and trained extensively on the most effective teaching methods
K12
 What K12 offers:
 Online tutoring
 Has a strong and effective partnership with public and private schools
 AdvancEDaccredited corporation meeting the highest standards of educational management
Kaplan Kids
 What Kaplan Kids offers:
 Online tutoring
 Customized learning plans
 RealTime Progress Reports track your child's progress
Kumon
 What Kumon offers:
 Incenter tutoring
 Individualized programs for your child
 Helps your child develop the skills and study habits needed to improve their academic performance
Sylvan Learning
 What Sylvan Learning offers:
 Online and incenter tutoring
 Sylvan tutors are certified teachers who provide personalized instruction
 Regular assessment and progress reports
Tutor Doctor
 What Tutor Doctor offers:
 InHome tutoring
 One on one attention by the tutor
 Develops personlized programs by working with your child's existing homework
TutorVista
 What TutorVista offers:
 Online tutoring
 Student works oneonone with a professional tutor
 Using the virtual whiteboard workspace to share problems, solutions and explanations