Solve Vertical Subtraction: 89 minus 9 Step-by-Step

Q: Why is the answer 80 and not 81?

When subtracting $89 - 9$, you're taking away 9 units. 9 - 9 = 0 in the units place, and 8 - 0 = 8 in the tens place, giving you 80.

Q: Do I need to borrow when subtracting 9 from 89?

No borrowing needed! Since we're subtracting 9 (which is 09), we have 9 - 9 = 0 in units and 8 - 0 = 8 in tens. Borrowing is only needed when the bottom digit is larger than the top digit.

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

Use addition to check: Add your answer to the number you subtracted. For example: $80 + 9 = 89$ ✓ This matches our original number!

Q: What if I wrote 89 - 09 instead?

That's actually more clear! Writing 9 as 09 helps you see that you're subtracting 0 tens and 9 units, making the place value alignment obvious.

Q: Is there a faster way than column subtraction?

For mental math, you can think: 89 - 9 means "take away 9 from the 9 in 89, leaving 80." But column method helps avoid mistakes with larger problems!

Vertical Subtraction with Two-Digit Numbers

$\begin{aligned} &89 \\ -& \\ &~~9 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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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 calculate subtraction of 2 digits, and then place

00:06 Let's start by subtracting ones from ones, and place in ones

00:09 Place 0 in the missing digits

00:13 Subtract tens from tens, and place in tens

00:16 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

$\begin{aligned} &89 \\ -& \\ &~~9 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

To find the result of subtracting 9 from 89, we will look at it digit by digit:

Step 1: Subtract the units digits:
9 - 9 = 0.
Step 2: Subtract the tens digits:
8 - 0 = 8.

The subtraction does not require any borrowing since both digits are smaller than or equal to the digits we are subtracting from.

Thus, the result of the subtraction $89 - 9$ is $80$ .

Considering the given multiple-choice options, the correct choice is option 4: $80$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Always subtract units digits first, then tens digits
Technique: Line up place values: 89 - 9 becomes 9-9=0, 8-0=8
Check: Add your answer to subtrahend: 80 + 9 = 89 ✓

Common Mistakes

Avoid these frequent errors

Subtracting larger digit from smaller digit incorrectly
Don't subtract 9 from 8 in the tens place = negative result! The 9 is only in the units place, so the tens digit of 9 is actually 0. Always align digits by place value before subtracting.

Practice Quiz

Test your knowledge with interactive questions

$\begin{aligned} &105 \\ -& \\ &~~~~3 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

FAQ

Everything you need to know about this question

Why is the answer 80 and not 81?

When subtracting $89 - 9$ , you're taking away 9 units. 9 - 9 = 0 in the units place, and 8 - 0 = 8 in the tens place, giving you 80.

Do I need to borrow when subtracting 9 from 89?

No borrowing needed! Since we're subtracting 9 (which is 09), we have 9 - 9 = 0 in units and 8 - 0 = 8 in tens. Borrowing is only needed when the bottom digit is larger than the top digit.

How do I check if my subtraction is correct?

Use addition to check: Add your answer to the number you subtracted. For example: $80 + 9 = 89$ ✓ This matches our original number!

What if I wrote 89 - 09 instead?

That's actually more clear! Writing 9 as 09 helps you see that you're subtracting 0 tens and 9 units, making the place value alignment obvious.

Is there a faster way than column subtraction?

For mental math, you can think: 89 - 9 means "take away 9 from the 9 in 89, leaving 80." But column method helps avoid mistakes with larger problems!

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