Solve the Decimal Addition: 0.2 + 0.1

Q: Why can't I just add 2 + 1 and put a decimal anywhere?

Because place value matters! The 2 in 0.2 means 2 tenths, not 2 ones. You must keep decimals in their correct positions to get the right answer.

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

No problem! Just align the decimal points and imagine zeros in empty places. For example: 0.2 + 0.15 becomes 0.20 + 0.15 when aligned.

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

The decimal point in your answer goes directly below the decimal points in the problem. If you align them properly, it lines up automatically!

Q: Can I check my answer a different way?

Yes! Convert to fractions: $ 0.2 = \frac{2}{10} $ and $ 0.1 = \frac{1}{10} $, so $ \frac{2}{10} + \frac{1}{10} = \frac{3}{10} = 0.3 $

Q: What if I get confused about tenths, hundredths, etc.?

Remember the pattern: the first digit after the decimal is tenths, the second is hundredths, third is thousandths. Count the places from the decimal point!

Decimal Addition with Tenths Place

$0.2+0.1=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:04 Let's solve this problem step by step.

00:08 First, we'll use long addition to solve this carefully. Remember to line up the numbers neatly.

00:15 Next, let's pay attention to the decimal points. Make sure they're lined up perfectly in a straight line.

00:22 Now, we'll start from the right side, adding the smallest digits first, just like we always do.

00:28 Keep going from right to left, carrying over numbers when needed. Take your time with each column.

00:35 And there we have it! That's our final answer. Great job following along!

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$0.2+0.1=$

Step-by-step solution

To solve this problem, we need to add the decimal numbers $0.2$ and $0.1$ .

Here are the steps to perform the addition:

Step 1: Align the numbers by their decimal points:
$0.2$
+ $0.1$
Step 2: Start adding from the rightmost digit to the left:

The tenths column contains 2 tenths (from $0.2$ ) and 1 tenth (from $0.1$ ), and adding these gives 3 tenths. There is no carryover since the result is below 10 tenths.
The single whole number place doesn't have digits to sum aside from the carry, which in this case, is zero.

Step 3: The sum of $0.2 + 0.1$ is $0.3$ .

Therefore, the solution to the problem is $0.3$ .

Final Answer

0.3

Key Points to Remember

Essential concepts to master this topic

Alignment Rule: Line up decimal points before adding numbers
Column Method: Add tenths place: 2 tenths + 1 tenth = 3 tenths
Verification: Check by converting to fractions: 2/10 + 1/10 = 3/10 = 0.3 ✓

Common Mistakes

Avoid these frequent errors

Adding digits without aligning decimal points
Don't just add 2 + 1 = 3 and write any decimal placement = wrong answer like 2.1! This ignores place value completely. Always align decimal points vertically first, then add column by column.

Practice Quiz

Test your knowledge with interactive questions

Determine whether the exercise is written correctly in relation to the position of the decimal point:

FAQ

Everything you need to know about this question

Why can't I just add 2 + 1 and put a decimal anywhere?

Because place value matters! The 2 in 0.2 means 2 tenths, not 2 ones. You must keep decimals in their correct positions to get the right answer.

What if the decimal numbers have different numbers of digits?

No problem! Just align the decimal points and imagine zeros in empty places. For example: 0.2 + 0.15 becomes 0.20 + 0.15 when aligned.

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

The decimal point in your answer goes directly below the decimal points in the problem. If you align them properly, it lines up automatically!

Can I check my answer a different way?

Yes! Convert to fractions: $0.2 = \frac{2}{10}$ and $0.1 = \frac{1}{10}$ , so $\frac{2}{10} + \frac{1}{10} = \frac{3}{10} = 0.3$

What if I get confused about tenths, hundredths, etc.?

Remember the pattern: the first digit after the decimal is tenths, the second is hundredths, third is thousandths. Count the places from the decimal point!

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