Solve Decimal Subtraction: Finding 0.2 - 0.1

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

Lining up decimal points ensures you're subtracting the same place values! Tenths from tenths, hundredths from hundredths. Without alignment, you'd be mixing up place values.

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

Add zeros to make them the same length! For example, 0.2 becomes 0.20 when subtracting from 0.25. This helps keep everything aligned properly.

Q: How can I check if my decimal subtraction is correct?

Use addition to check! Add your answer to the number you subtracted. If you get back to your starting number, you're right: $ 0.1 + 0.1 = 0.2 $ ✓

Q: Is 0.1 the same as 1/10?

Yes! $ 0.1 = \frac{1}{10} $. Both represent one-tenth. Sometimes thinking in fractions can help verify decimal operations.

Q: What if I get confused with the decimal placement?

Count the decimal places! In $ 0.2 - 0.1 $, both numbers have 1 decimal place, so your answer should also have 1 decimal place: 0.1

Decimal Subtraction with Aligned Place Values

$0.2-0.1=$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 We'll use long subtraction for calculation

00:09 We'll place the decimal point in the appropriate position

00:12 We'll start by subtracting the corresponding smallest digits

00:15 We'll place and continue to subtract and calculate

00:20 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

$0.2-0.1=$

Step-by-step solution

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

Step 1: Identify the decimal numbers involved, which are $0.2$ and $0.1$ .
Step 2: Align the decimal points for the numbers vertically and perform the subtraction.

Now, let's proceed with the calculation:

$0.2 - 0.1 = 0.1$ The operation involves subtracting $0.1$ from $0.2$ by aligning the decimal points. Since both numbers have only one decimal place, the decimals align easily, making the subtraction straightforward.

Therefore, the result of the subtraction
$0.2 - 0.1$ is $0.1$ .

The correct choice from the given options is Choice 2: $0.1$ .

Final Answer

0.1

Key Points to Remember

Essential concepts to master this topic

Rule: Line up decimal points vertically before subtracting
Technique: Subtract column by column: 0.2 - 0.1 = 0.1
Check: Add result to subtrahend: 0.1 + 0.1 = 0.2 ✓

Common Mistakes

Avoid these frequent errors

Ignoring decimal point alignment
Don't subtract digits without aligning decimal points = 2 - 1 = 1 instead of 0.1! This treats decimals like whole numbers and gives answers 10 times too large. Always line up decimal points first.

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?

Lining up decimal points ensures you're subtracting the same place values! Tenths from tenths, hundredths from hundredths. Without alignment, you'd be mixing up place values.

What if the decimals have different numbers of digits?

Add zeros to make them the same length! For example, 0.2 becomes 0.20 when subtracting from 0.25. This helps keep everything aligned properly.

How can I check if my decimal subtraction is correct?

Use addition to check! Add your answer to the number you subtracted. If you get back to your starting number, you're right: $0.1 + 0.1 = 0.2$ ✓

Is 0.1 the same as 1/10?

Yes! $0.1 = \frac{1}{10}$ . Both represent one-tenth. Sometimes thinking in fractions can help verify decimal operations.

What if I get confused with the decimal placement?

Count the decimal places! In $0.2 - 0.1$ , both numbers have 1 decimal place, so your answer should also have 1 decimal place: 0.1

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