Solve Vertical Subtraction: 358 minus 79 Step-by-Step

Q: What does 'borrowing' actually mean in subtraction?

Borrowing means taking 1 from the next column to the left, which equals 10 in the current column. So when you borrow 1 ten, you get 10 ones to work with!

Q: Why do I start from the right side?

You start from the ones column because that's how our number system works! Just like when you count money, you handle pennies before dimes, and dimes before dollars.

Q: What if I need to borrow from zero?

When borrowing from 0, you need to keep borrowing from columns to the left until you find a digit greater than 0. Then work backwards, turning 0s into 9s along the way.

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

Use addition to check! Add your answer to the number you subtracted. If you get the original number, you're correct: $279 + 79 = 358$ ✓

Q: What if I forget to reduce the borrowed-from digit?

This creates wrong answers! Always remember to reduce the digit you borrowed from by 1. Write the new digit above the original to keep track.

Vertical Subtraction with Regrouping

$\begin{aligned} &358 \\ -& \\ &~~79 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 Each time consider a shortage of 2 digits, and then place

00:06 8 is less than 9

00:11 Therefore subtract 1 from the tens, and add this amount to the ones

00:17 In other words, now instead of 8 we will have 18

00:20 Subtract the ones from the ones plus ten

00:24 Place in ones

00:31 4 is less than 7

00:36 Therefore subtract 1 from the hundreds, and add this amount to the tens

00:42 In other words, now instead of 4 we will have 14

00:48 Subtract the tens from the tens plus ten

00:51 Place in tens

00:54 Place 0 in the missing digits

00:57 Subtract hundreds from hundreds, and place in hundreds

01:03 And this is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$\begin{aligned} &358 \\ -& \\ &~~79 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

To solve this subtraction problem, we'll perform vertical subtraction with regrouping as necessary:

Step 1: Align the numbers vertically, ensuring that digits are in the correct place value columns.
Step 2: Begin with the units column: Subtract 9 from 8. Since 8 is smaller than 9, we need to regroup by borrowing from the tens column.

We take 1 ten from 5 in the tens column. The tens digit becomes 4, and we add 10 to 8 in the units column, making it 18.
Now, subtract 9 from 18, which equals 9.

Step 3: Move to the tens column: Subtract 7 from 4 (after borrowing). Since 4 is smaller than 7, we need to regroup again.

We borrow 1 hundred from the hundreds column; 3 becomes 2. The tens digit becomes 14.
Now, subtract 7 from 14, which equals 7.

Step 4: Finally, handle the hundreds column: Subtract 0 from 2 (after borrowing), resulting in 2.

Therefore, the solution to the subtraction is $279$ .

Final Answer

279

Key Points to Remember

Essential concepts to master this topic

Regrouping Rule: Borrow from the next column when subtracting larger digits
Column Technique: Work right to left, 18 - 9 = 9 after borrowing
Check: Add your answer to the subtracted number: 279 + 79 = 358 ✓

Common Mistakes

Avoid these frequent errors

Subtracting smaller digit from larger digit regardless of position
Don't subtract 8 - 9 = 1 by flipping the order = wrong answer 281! This ignores place value rules and creates incorrect digits. Always borrow from the next column when the top digit is smaller.

Practice Quiz

Test your knowledge with interactive questions

$\begin{aligned} &15 \\ -& \\ &~~4 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

FAQ

Everything you need to know about this question

What does 'borrowing' actually mean in subtraction?

Borrowing means taking 1 from the next column to the left, which equals 10 in the current column. So when you borrow 1 ten, you get 10 ones to work with!

Why do I start from the right side?

You start from the ones column because that's how our number system works! Just like when you count money, you handle pennies before dimes, and dimes before dollars.

What if I need to borrow from zero?

When borrowing from 0, you need to keep borrowing from columns to the left until you find a digit greater than 0. Then work backwards, turning 0s into 9s along the way.

How can I check if my subtraction is correct?

Use addition to check! Add your answer to the number you subtracted. If you get the original number, you're correct: $279 + 79 = 358$ ✓

Is there a way to do this without borrowing?

Not for this problem! When the top digit is smaller than the bottom digit, borrowing is required. It's a fundamental part of the subtraction algorithm.

What if I forget to reduce the borrowed-from digit?

This creates wrong answers! Always remember to reduce the digit you borrowed from by 1. Write the new digit above the original to keep track.

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