Calculate Rectangle Area: 15 cm × 3 cm Dimensions

Rectangle Area with Given Dimensions

The width of a rectangle is equal to 15 cm and its length is 3 cm.

Calculate the area of the rectangle.

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:08 Let's find the area of this rectangle.
00:11 To do this, we use the formula: length times width. So get ready to apply it.
00:18 Now, substitute the given numbers for length and width, and calculate the area.
00:23 Great job! That's how we find the area of a rectangle.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

The width of a rectangle is equal to 15 cm and its length is 3 cm.

Calculate the area of the rectangle.

2

Step-by-step solution

To calculate the area of the rectangle, we multiply the length by the width:

15×3=45 15\times3=45

3

Final Answer

45

Key Points to Remember

Essential concepts to master this topic
  • Formula: Area = length × width for all rectangles
  • Technique: Multiply 15 cm × 3 cm = 45 cm²
  • Check: Units should be square units (cm²) and result should be positive ✓

Common Mistakes

Avoid these frequent errors
  • Adding dimensions instead of multiplying
    Don't add 15 + 3 = 18! This gives perimeter calculation, not area. Area measures the space inside the rectangle, which requires multiplication. Always multiply length × width for area.

Practice Quiz

Test your knowledge with interactive questions

Look at the rectangle ABCD below.

Side AB is 6 cm long and side BC is 4 cm long.

What is the area of the rectangle?
666444AAABBBCCCDDD

FAQ

Everything you need to know about this question

Why do we multiply length and width instead of adding them?

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Area measures the space inside a shape. When you multiply 15 × 3, you're finding how many square centimeters fit inside. Adding gives you perimeter - the distance around the outside.

Does it matter which dimension I call length or width?

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No! For rectangles, length × width = width × length. Whether you do 15 × 3 or 3 × 15, you'll get the same area of 45 cm².

Why are the units cm² instead of just cm?

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Area is measured in square units because we're multiplying two lengths together. cm × cm = cm². This tells us we're measuring a 2-dimensional space, not just a distance.

How can I visualize this calculation?

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Imagine the rectangle divided into unit squares. You have 15 rows with 3 squares in each row, giving you 15 × 3 = 45 total unit squares!

What if I get the dimensions mixed up?

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Don't worry! Since multiplication is commutative, 15 × 3 = 3 × 15. The area will be correct regardless of which dimension you multiply first.

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