Solve Decimal Subtraction: 1.5 - 0.7 Step-by-Step

Q: Why do I need to borrow when subtracting decimals?

You borrow when the bottom digit is larger than the top digit. In 1.5 - 0.7, we can't subtract 7 from 5 in the tenths place, so we borrow 1 from the ones place to make it 15 - 7 = 8.

Q: What happens to the 1 in 1.5 when I borrow?

When you borrow 1 from the ones place, the 1 becomes 0 and the 5 in the tenths place becomes 15. So 1.5 temporarily becomes 0.15 for the subtraction step.

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 the original number, you're right: $ 0.8 + 0.7 = 1.5 $ ✓

Q: Do I always need to borrow in decimal subtraction?

No! You only borrow when the top digit is smaller than the bottom digit. For example, in 1.8 - 0.3, you don't need to borrow because 8 > 3.

Q: What if both numbers have different amounts of decimal places?

Add zeros as placeholders to make them equal. For example, treat 1.5 as 1.50 when subtracting from a number like 2.75. This helps with alignment!

Decimal Subtraction with Borrowing

$1.5-0.7=$

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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

00:07 Place the decimal point in the appropriate position

00:10 The digit is smaller than the digit we need to subtract from

00:13 So we'll borrow from the next digit

00:16 The larger digit will decrease by 1, and our digit will increase by 10

00:20 Now we'll subtract from the larger number and place it

00:32 We'll continue to subtract and place accordingly

00:41 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

$1.5-0.7=$

Step-by-step solution

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

Step 1: Identify the given numbers 1.5 and 0.7.
Step 2: Align the decimal points of the numbers.
Step 3: Subtract the numbers digit by digit from right to left.

Now, let's work through each step:
Step 1: The problem gives us the numbers 1.5 and 0.7, which need to be subtracted from each other.
Step 2: Write them vertically one on top of the other, aligning the decimal points:
$1.5$
$- 0.7$
Step 3: Subtract from right to left starting from the tenths place. In the tenths place, subtract $7$ from $5$ , which requires borrowing since $5 < 7$ .
- Borrow 1 from the units place of $1.5$ , making it $0.5 + 1.0 = 10.5$ , and giving the tenths place $15$
- Now we have:
$(1.0 - 0.1)$ in the units, and $15 - 7 = 8$ in the tenths.
our expression becomes 0.8 after subtraction.

Therefore, the solution to the problem is $0.8$ .

Final Answer

0.8

Key Points to Remember

Essential concepts to master this topic

Alignment: Always line up decimal points vertically before subtracting
Borrowing: When subtracting 7 from 5, borrow 1 to make 15 - 7 = 8
Verification: Add your answer to the subtracted number: 0.8 + 0.7 = 1.5 ✓

Common Mistakes

Avoid these frequent errors

Not aligning decimal points properly
Don't line up the rightmost digits like whole numbers = wrong place values! This puts tenths in ones place and gives answers like 8 instead of 0.8. Always align the decimal points directly above each other.

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 do I need to borrow when subtracting decimals?

You borrow when the bottom digit is larger than the top digit. In 1.5 - 0.7, we can't subtract 7 from 5 in the tenths place, so we borrow 1 from the ones place to make it 15 - 7 = 8.

What happens to the 1 in 1.5 when I borrow?

When you borrow 1 from the ones place, the 1 becomes 0 and the 5 in the tenths place becomes 15. So 1.5 temporarily becomes 0.15 for the subtraction step.

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 the original number, you're right: $0.8 + 0.7 = 1.5$ ✓

Do I always need to borrow in decimal subtraction?

No! You only borrow when the top digit is smaller than the bottom digit. For example, in 1.8 - 0.3, you don't need to borrow because 8 > 3.

What if both numbers have different amounts of decimal places?

Add zeros as placeholders to make them equal. For example, treat 1.5 as 1.50 when subtracting from a number like 2.75. This helps with alignment!

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