Solve Vertical Addition: 36 + 43 Step-by-Step

Q: Why do I start adding from the right side?

Starting from the units place (rightmost column) lets you handle any carrying properly. If you get a sum over 9, you need to carry to the next column, which only works going right to left!

Q: What if I get confused about which numbers go where?

Line up the numbers by place value! The units digits (6 and 3) should be in the same column, and the tens digits (3 and 4) should be in the same column.

Q: How do I know if I need to carry?

You need to carry when the sum of digits in any column is 10 or greater. In this problem, $ 6 + 3 = 9 $ and $ 3 + 4 = 7 $, so no carrying needed!

Q: Can I add the numbers horizontally instead?

Yes, but vertical alignment is much clearer for multi-digit addition! It helps you see place values and makes carrying easier when you have larger numbers.

Q: What's the fastest way to check my answer?

Try mental math for a quick check: 36 is close to 40, and 43 is close to 40, so $ 40 + 40 = 80 $. Since 79 is close to 80, it makes sense!

Addition Algorithm with Two-Digit Numbers

$\begin{aligned} &36 \\ +& \\ &43 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:04 Let's solve this math problem together.

00:08 First, we'll add the ones place digits.

00:11 Make sure you place the sum in the correct position.

00:15 Next, add the tens place digits together.

00:19 Carefully place this sum as well.

00:23 And there you have it. We've solved the problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

$\begin{aligned} &36 \\ +& \\ &43 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

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

Step 1: Add the units place digits (rightmost column) of both numbers: 6 (from 36) and 3 (from 43).
Step 2: Calculate $6 + 3 = 9$ . Place 9 under the units column.
Step 3: Add the tens place digits (left side) of both numbers: 3 (from 36) and 4 (from 43).
Step 4: Calculate $3 + 4 = 7$ . Place 7 under the tens column.

Now, let's work through each step:
Step 1: Add the rightmost digits, 6 and 3, to get 9.
Step 2: Since the sum is less than 10, we write 9 immediately below the line.
Step 3: Proceed with the tens digits. Add 3 and 4 to get 7.
Step 4: Since there's no carrying involved, write 7 in the result's tens column.

Thus, the solution to the addition problem is $79$ , corresponding to choice 4.

Final Answer

Key Points to Remember

Essential concepts to master this topic

Place Value: Always align numbers by place value columns
Technique: Add units first: $6 + 3 = 9$ , then tens: $3 + 4 = 7$
Check: Verify by adding in reverse order: $43 + 36 = 79$ ✓

Common Mistakes

Avoid these frequent errors

Adding left to right instead of right to left
Don't start with tens place first = confusion with carrying! This leads to errors when regrouping is needed. Always start from the rightmost column (units) and work left.

Practice Quiz

Test your knowledge with interactive questions

$\begin{aligned} &90 \\ +& \\ &~~9\\ &\underline{\phantom{776}} & \\ \end{aligned}$

FAQ

Everything you need to know about this question

Why do I start adding from the right side?

Starting from the units place (rightmost column) lets you handle any carrying properly. If you get a sum over 9, you need to carry to the next column, which only works going right to left!

What if I get confused about which numbers go where?

Line up the numbers by place value! The units digits (6 and 3) should be in the same column, and the tens digits (3 and 4) should be in the same column.

How do I know if I need to carry?

You need to carry when the sum of digits in any column is 10 or greater. In this problem, $6 + 3 = 9$ and $3 + 4 = 7$ , so no carrying needed!

Can I add the numbers horizontally instead?

Yes, but vertical alignment is much clearer for multi-digit addition! It helps you see place values and makes carrying easier when you have larger numbers.

What's the fastest way to check my answer?

Try mental math for a quick check: 36 is close to 40, and 43 is close to 40, so $40 + 40 = 80$ . Since 79 is close to 80, it makes sense!

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