Solve Decimal Addition: 5.1 + 2.3 Step by Step

Q: Why do I need to line up the decimal points?

Decimal points must align so that like place values add together! When decimal points line up, tenths add to tenths and ones add to ones, just like in regular addition.

Q: What if the decimal numbers have different amounts of digits?

No problem! You can add zeros as placeholders. For example, $ 5.1 $ can be written as $ 5.10 $ if needed for alignment.

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

The decimal point in your answer goes in the same column as the decimal points in the numbers you're adding. It lines up perfectly!

Q: Do I add from left to right or right to left?

Always add from right to left, just like with whole numbers! Start with the rightmost column (tenths), then move left to ones, tens, etc.

Q: What if I get confused about which column is which?

Remember the pattern: ones, tenths, hundredths. The first digit after the decimal is always tenths, and before the decimal is always ones.

Decimal Addition with Place Value Alignment

$\text{5}.1+2.3=$

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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

00:11 We will place the decimal point in the appropriate position

00:14 We will start by adding the smallest appropriate digits

00:18 We will place and continue to add and calculate

00:22 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

$\text{5}.1+2.3=$

Step-by-step solution

To solve this problem, let's follow these steps for decimal addition:

Step 1: Align the decimals of the numbers vertically, so that both $5.1$ and $2.3$ have their decimal points in the same position:

5.1
+ 2.3
---------

Step 2: Start adding from the rightmost column (the tenths position). Add the tenths: $1 + 3 = 4$ .
Step 3: Move to the left to add the units: $5 + 2 = 7$ .

Put these sums together, and we have:

5.1
+ 2.3
---------
7.4

Therefore, the sum of $5.1$ and $2.3$ is $7.4$ . This matches choice $\text{3}$ .

Thus, the correct answer is $7.4$ .

Final Answer

7.4

Key Points to Remember

Essential concepts to master this topic

Alignment Rule: Line up decimal points vertically before adding
Technique: Add column by column: tenths 1+3=4, ones 5+2=7
Check: Count decimal places: both numbers have 1, answer has 1 ✓

Common Mistakes

Avoid these frequent errors

Adding without aligning decimal points
Don't just line up the right edges like whole numbers = wrong place values! This puts tenths in different columns and gives answers like 8.4 instead of 7.4. Always align the decimal points first, then add each column.

Practice Quiz

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FAQ

Everything you need to know about this question

Why do I need to line up the decimal points?

Decimal points must align so that like place values add together! When decimal points line up, tenths add to tenths and ones add to ones, just like in regular addition.

What if the decimal numbers have different amounts of digits?

No problem! You can add zeros as placeholders. For example, $5.1$ can be written as $5.10$ if needed for alignment.

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

The decimal point in your answer goes in the same column as the decimal points in the numbers you're adding. It lines up perfectly!

Do I add from left to right or right to left?

Always add from right to left, just like with whole numbers! Start with the rightmost column (tenths), then move left to ones, tens, etc.

What if I get confused about which column is which?

Remember the pattern: ones, tenths, hundredths. The first digit after the decimal is always tenths, and before the decimal is always ones.

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Solve Decimal Addition: 5.1 + 2.3 Step by Step

Decimal Addition with Place Value Alignment

❤️ Continue Your Math Journey!

Step-by-step video solution

Step-by-step written solution

Understand the problem

Step-by-step solution

Final Answer

Key Points to Remember

Common Mistakes

Practice Quiz

FAQ

Why do I need to line up the decimal points?

What if the decimal numbers have different amounts of digits?

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

Do I add from left to right or right to left?

What if I get confused about which column is which?

🌟 Unlock Your Math Potential

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