Decimal Addition Problem: Solve 0.5 + 0.3

Q: Why can't I just add 5 + 3 = 8 and put a decimal somewhere?

Because the position of digits matters! Both 0.5 and 0.3 represent tenths, so you're really adding 5 tenths + 3 tenths = 8 tenths, which is 0.8.

Q: What if the decimal numbers have different lengths?

No problem! You can add zeros as placeholders. For example, 0.5 can be written as 0.50, making it easier to align with longer decimals like 0.325.

Q: How do I know where to put the decimal point in my answer?

The decimal point in your answer goes in the same position as the aligned decimal points in your problem. If you line them up correctly, the answer's decimal point lines up too!

Q: Can I check my answer a different way?

Yes! Convert to fractions: $ 0.5 = \frac{5}{10} $ and $ 0.3 = \frac{3}{10} $, so $ \frac{5}{10} + \frac{3}{10} = \frac{8}{10} = 0.8 $

Q: What's the difference between 0.8 and 0.80?

They're exactly the same value! Adding zeros after the last digit in a decimal doesn't change its value, just like 8.0 equals 8.

Decimal Addition with Place Value Alignment

$0.5+0.3=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 We will use long addition for calculation

00:08 We will place the decimal point in the appropriate position

00:11 We will start by adding the smallest appropriate digits

00:15 We will place and continue to add and calculate

00:19 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$0.5+0.3=$

Step-by-step solution

To solve this problem, follow these steps:

Step 1: Align the numbers vertically by their decimal point. Write $0.5$ and $0.3$ ensuring the decimal points are aligned.
Step 2: Perform the addition:
0.5
+ 0.3
—---------
Step 3: Add the numbers starting from the right (tenths place):
- Add $0.5 + 0.3 = 0.8$ .

Therefore, the sum of $0.5$ and $0.3$ is $0.8$ .

Final Answer

0.8

Key Points to Remember

Essential concepts to master this topic

Rule: Always align decimal points vertically when adding decimal numbers
Technique: Add digits column by column: 5 tenths + 3 tenths = 8 tenths
Check: Count total tenths: 0.5 has 5 tenths, 0.3 has 3 tenths, total 8 tenths = 0.8 ✓

Common Mistakes

Avoid these frequent errors

Adding decimal digits without aligning decimal points
Don't just add 5 + 3 = 8 and write 0.8! Without proper alignment, students might get confused about place values and write wrong answers like 3.5 or 5.3. Always line up the decimal points first, then add column by column.

Practice Quiz

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FAQ

Everything you need to know about this question

Why can't I just add 5 + 3 = 8 and put a decimal somewhere?

Because the position of digits matters! Both 0.5 and 0.3 represent tenths, so you're really adding 5 tenths + 3 tenths = 8 tenths, which is 0.8.

What if the decimal numbers have different lengths?

No problem! You can add zeros as placeholders. For example, 0.5 can be written as 0.50, making it easier to align with longer decimals like 0.325.

How do I know where to put the decimal point in my answer?

The decimal point in your answer goes in the same position as the aligned decimal points in your problem. If you line them up correctly, the answer's decimal point lines up too!

Can I check my answer a different way?

Yes! Convert to fractions: $0.5 = \frac{5}{10}$ and $0.3 = \frac{3}{10}$ , so $\frac{5}{10} + \frac{3}{10} = \frac{8}{10} = 0.8$

What's the difference between 0.8 and 0.80?

They're exactly the same value! Adding zeros after the last digit in a decimal doesn't change its value, just like 8.0 equals 8.

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