Decimal Point Alignment: Verifying 21.52 + 3.4 Addition Setup

Decimal Addition with Proper Alignment

Determine whether the exercise is correctly written or not.

True or false:

The positions of the decimal points correspond.

21.52+3.4

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:12 Let's check if the decimal points are in the right place.
00:16 In long subtraction, make sure the decimal points are lined up perfectly.
00:21 Great job! The decimal points are aligned correctly.
00:25 And that's the solution to our problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Determine whether the exercise is correctly written or not.

True or false:

The positions of the decimal points correspond.

21.52+3.4

2

Step-by-step solution

First let's fill in the zeros in the empty spaces as follows:

21.52+03.40 21.52\\+03.40\\ Note that the decimal points are written one below the other.

Therefore, the positions of the decimal points correspond and thus the exercise is written in the correct form.

3

Final Answer

True

Key Points to Remember

Essential concepts to master this topic
  • Rule: Decimal points must be aligned vertically before adding
  • Technique: Add trailing zeros: 3.4 becomes 3.40 to match 21.52
  • Check: Verify decimal points line up perfectly in columns ✓

Common Mistakes

Avoid these frequent errors
  • Not aligning decimal points vertically
    Don't just line up the last digits without checking decimal placement = wrong sum! This treats numbers as if they have different place values. Always align decimal points first, then add trailing zeros as needed.

Practice Quiz

Test your knowledge with interactive questions

\( \text{0.6+0}.5= \)

+=

FAQ

Everything you need to know about this question

Why can't I just line up the numbers on the right side?

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Because decimal numbers need place value alignment! When you line up on the right, you might be adding tenths to hundredths, which gives the wrong answer.

What if the numbers have different amounts of decimal places?

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Add trailing zeros to make them the same length! For example, 3.4 becomes 3.40 when adding to 21.52. This doesn't change the value, just makes alignment clear.

Do I need to write the zeros or just imagine them?

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It's much safer to write them out! Writing 21.52+03.40 21.52 + 03.40 prevents mistakes and makes the alignment obvious to check.

How do I know if my decimal points are properly aligned?

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Draw an imaginary vertical line through all the decimal points. If they all line up perfectly on this line, your setup is correct!

What happens if I don't align the decimal points?

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You'll get the wrong answer! For example, treating 3.4 as 34 would give you 21.52 + 34 = 55.52 instead of the correct 24.92.

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