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## 7th grade foundations (Eureka Math/EngageNY)

### Course: 7th grade foundations (Eureka Math/EngageNY)>Unit 6

Lesson 4: Topic E: Foundations

# Volume through decomposition

Sal finds the volume of an irregular 3D figure by breaking the figure into 2 rectangular prisms and finding the volume of each part.

## Want to join the conversation?

• imagine using khan academy in 2022,(plz up vote my comment so every one can see it, thanks)
• imagine cant be me
• I freaked out when I got an irregular shape homework but after I watched this video, I did perfectly on it. Before the video, I thought that I had to add the numbers together but when I watched the video, I understood that I had to break the irregular shapes apart and multiply the length,width, and height to get the volume and add both of the shape’s volume to get the answer.
• Okay.

Sometimes you want to know how much space a 3d shape takes up. Now maybe you know how to figure out how much space a box takes up, or a pyramid, or a cylinder or something - but then somebody gives you some weird L-shaped thing! What do you do?

Well, you can look at the weird object, and realize that it's kind of like if you stuck two boxes together. And if you can figure out how big those boxes are, you can just figure out their volumes, add those volumes together, and you've got the volume of the bigger object.

It's about taking a big problem and breaking it into smaller problems that you can solve easier.
• Does the order I multiply the width, height and depth matter to find the volume?
• No, the order of multiplication of width, height, and depth does not matter, because multiplication is commutative and associative.

Have a blessed, wonderful day!
• If common sense is so common, why do so few people have it?
• how dare you
(1 vote)
• I still don't get it and why so many steps.
• What I'm doing is multiplying the length, width, and height of the two forms (it may be one). I'll find the volume by doing this. Next I'll add both the volumes together and find the volume of the irregular form.
• i dont understand this stuff its really hard