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### Course: MAP Recommended Practice>Unit 24

Lesson 6: Decompose figures to find area

# Area word problem: house size

Sal decomposes an irregular shape to find area of entire figure. Created by Sal Khan.

## Want to join the conversation?

• In the video on calculating the square footage of a house, at how did you get the width of the green rectangle to be 25ft? Shouldn't it be 26ft, the same as the width of the blue one?
• At , why did we not include the 5? Is it because it did not have a rectangle to contribute to the problem in order to calculate the total area?
• The video didn't include the 5 because it is showing the length of the distance between the teal rectangle and the purple one. The purple rectangle already show the length and width(20 and 20). The 5 is also not the whole length of the rectangle. It is trying to throw you off.
• Maybe some of the confusion comes from the issue that many Third Graders have not yet learned how to multiply two, two digit numbers together (unless they are multiples of 10). My nephew was only able to calculate 20ft x 20ft so could not complete the above problem. The Third Grade multiplication section of this site only includes lessons on multiplying single digit multiplication problems so possibly this problem is advanced for the typical Third Grader?
• it is not to complicated because 6,555*6,555=42968225
• Why are you using a house as the example?
• because if you are a landscaper then you know how long your walls have to be or were the rooms would be, so thats probably why
• Why would you have an instructional video showing how to find the area of a house and then not have any practice problems following? I assume that to find the house size, one would have to apply both the addition and subtraction decomposition?
• because your mom is so stupid she can't even understand a simple explanation
• How does area Help us in the real world?
• Area helps you in the real world for construction projects, such building houses(shown in the video), for carpeting in your home, etc.
• How can I find the area of the House? I tried, but Igot it wrong.
:(
• It is in the video,we have to break it in different rectangles.
• I dont understand on how it's 15 ft
• find the length, width and perimeter of a room with an area measures 18.50 square meter?
• You need to be more specific. There are multiple answers to this question.
Here are a few (some of the more practical ones):
7.4m x 2.5m
9.25m x 2m
4.625m x 4m
• hey Sal, i thought the shape in pink is a square not a rectangle?
• A square is a certain kind of rectangle. A rectangle has four sides, two pairs of equal, parallel sides, and four right angles. A square fits this criteria.