Calculate the Sum: 6.4 + 2.56 Decimal Addition

Q: Why do I need to add a zero to make 6.4 into 6.40?

Adding zeros as placeholders helps you see each place value clearly! $6.4$ and $6.40$ have the same value, but $6.40$ makes it easier to line up with $2.56$.

Q: What if I forget to line up the decimal points?

You'll get the wrong answer! For example, if you add 6.4 + 2.56 without alignment, you might get $8.90$ instead of the correct $8.96$. Always draw a vertical line through the decimal points first.

Q: How many decimal places should my answer have?

Your answer should have the same number of decimal places as the number with the most decimal places. Since $2.56$ has 2 decimal places, your answer $8.96$ should also have 2.

Q: Can I add decimals from left to right instead?

It's better to add from right to left (smallest place value first) just like with whole numbers. This way, you can carry over correctly if any column adds up to 10 or more.

Decimal Addition with Different Place Values

$6.4\\+2.56$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:05 Let's solve this problem together.

00:08 We're going to use vertical addition for our calculation.

00:14 Make sure to write the numbers properly, with decimal points lined up.

00:18 First, start by adding the smallest digits on the right.

00:24 Calculate, then write down the result right below.

00:32 Keep adding, calculating, and writing the results carefully.

00:51 And there you have it! That's the answer to our question.

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$6.4\\+2.56$

Step-by-step solution

To solve this problem, we'll follow these steps:

Step 1: Align the numbers based on the decimal point.
Step 2: Perform addition starting from the rightmost digit, carrying over as necessary.
Step 3: Ensure the decimal point is placed correctly in the final answer.

Now, let's work through each step:

Step 1: Align the numbers vertically:

  6.40
+ 2.56
------

Step 2: Start with the hundredths place (rightmost) and move left.

Add the hundredths: $0 + 6 = 6$ .
Add the tenths: $4 + 5 = 9$ .
Add the units: $6 + 2 = 8$ .

Step 3: Place the decimal point directly below the other decimal points in the final answer.

  6.40
+ 2.56
------
  8.96

Therefore, the solution to the problem is $8.96$ .

Final Answer

8.96

Key Points to Remember

Essential concepts to master this topic

Alignment Rule: Line up decimal points vertically before adding digits
Technique: Add zeros as placeholders: 6.4 becomes 6.40 for alignment
Check: Count decimal places in answer matches longest original number ✓

Common Mistakes

Avoid these frequent errors

Adding decimals without proper alignment
Don't just line up the rightmost digits like 6.4 + 2.56 = 8.90! This ignores place values and gives wrong totals. Always align decimal points first, then add placeholders like 6.40 + 2.56.

Practice Quiz

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FAQ

Everything you need to know about this question

Why do I need to add a zero to make 6.4 into 6.40?

Adding zeros as placeholders helps you see each place value clearly! $6.4$ and $6.40$ have the same value, but $6.40$ makes it easier to line up with $2.56$ .

What if I forget to line up the decimal points?

You'll get the wrong answer! For example, if you add 6.4 + 2.56 without alignment, you might get $8.90$ instead of the correct $8.96$ . Always draw a vertical line through the decimal points first.

How many decimal places should my answer have?

Your answer should have the same number of decimal places as the number with the most decimal places. Since $2.56$ has 2 decimal places, your answer $8.96$ should also have 2.

Can I add decimals from left to right instead?

It's better to add from right to left (smallest place value first) just like with whole numbers. This way, you can carry over correctly if any column adds up to 10 or more.

What if I need to carry over when adding decimals?

Carrying works exactly the same as with whole numbers! If a column adds up to 10 or more, write down the ones digit and carry the tens digit to the next column on the left.

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