Solve Three-Digit Addition: 115 + 236 Using Vertical Format

Q: What does 'carrying' mean in addition?

When two digits add up to 10 or more, you write down the ones digit and 'carry' the tens digit to the next column. For example, $5 + 6 = 11$, so write 1 and carry 1.

Q: Why do I need to line up the numbers vertically?

Lining up by place value ensures you add ones to ones, tens to tens, and hundreds to hundreds. Misaligned numbers lead to completely wrong answers!

Q: How do I remember which direction to carry?

Always carry to the left - from ones to tens, tens to hundreds, etc. Think of it as moving to the next bigger place value column.

Q: Can I check my answer without doing the problem again?

Use estimation: 115 ≈ 100, 236 ≈ 200, so expect around 300Try subtraction: 351 - 236 should equal 115Add the digits: $3 + 5 + 1 = 9$ and $1 + 1 + 5 + 2 + 3 + 6 = 18$, which also adds to 9 ✓

Vertical Addition with Carrying Strategy

$\begin{aligned} &115 \\ +& \\ &236 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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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 we'll calculate the sum of 2 digits, and then substitute

00:06 Let's start by adding ones with ones

00:09 Substitute the ones, add 1 to the tens

00:14 Add tens with tens, remember to add 1 to the calculation

00:20 Substitute in the tens place

00:24 Add hundreds with hundreds, and substitute in the hundreds place

00:28 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

$\begin{aligned} &115 \\ +& \\ &236 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

To solve this problem, we'll use the following steps:

Step 1: Align the numbers 115 and 236 vertically by their place values:

$\begin{aligned} &115 \\ +&236 \\ &\underline{\phantom{776}} \\ \end{aligned}$

Step 2: Start by adding the digits in the units (right-most) column:
$5 + 6 = 11$
Write 1 in the units place and carry over 1 to the tens column.

Step 3: Add the digits in the tens column with the carry:
$1 + 3 + 1 = 5$
Write 5 in the tens place.

Step 4: Add the digits in the hundreds column:
$1 + 2 = 3$
Write 3 in the hundreds place.

Putting it all together, we have:
$\begin{aligned} &115 \\ +&236 \\ &\underline{351} \\ \end{aligned}$

Therefore, the sum of 115 and 236 is $\textbf{351}$ . The correct choice is option 3.

Final Answer

351

Key Points to Remember

Essential concepts to master this topic

Place Value Alignment: Stack numbers by ones, tens, hundreds columns
Carrying Technique: When 5 + 6 = 11, write 1 and carry 1
Verification Check: Add left to right: 100 + 200 + 10 + 30 + 5 + 6 = 351 ✓

Common Mistakes

Avoid these frequent errors

Forgetting to carry over when digits sum to 10 or more
Don't write 11 in the ones place when 5 + 6 = 11! This creates impossible two-digit place values and wrong totals. Always write the ones digit and carry the tens digit to the next column.

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

What does 'carrying' mean in addition?

When two digits add up to 10 or more, you write down the ones digit and 'carry' the tens digit to the next column. For example, $5 + 6 = 11$ , so write 1 and carry 1.

Why do I need to line up the numbers vertically?

Lining up by place value ensures you add ones to ones, tens to tens, and hundreds to hundreds. Misaligned numbers lead to completely wrong answers!

How do I remember which direction to carry?

Always carry to the left - from ones to tens, tens to hundreds, etc. Think of it as moving to the next bigger place value column.

What if I forget to add the carried number?

Your answer will be too small! In this problem, forgetting the carried 1 in the tens column gives you $1 + 3 = 4$ instead of $1 + 3 + 1 = 5$ , making the answer 341 instead of 351.

Can I check my answer without doing the problem again?

Use estimation: 115 ≈ 100, 236 ≈ 200, so expect around 300
Try subtraction: 351 - 236 should equal 115
Add the digits: $3 + 5 + 1 = 9$ and $1 + 1 + 5 + 2 + 3 + 6 = 18$ , which also adds to 9 ✓

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