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

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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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