Solve Two-Digit Addition: 23 + 59 Using Column Method

Q: What does 'carry over' mean when adding?

When a column adds up to 10 or more, you write the units digit in that column and carry the tens digit to the next column left. Think of it as borrowing space!

Q: Why do I need to align the numbers vertically?

Aligning by place value ensures you're adding units to units and tens to tens. If numbers aren't aligned, you'll add the wrong digits together!

Q: What if I forget to add the carried number?

You'll get the wrong answer! Always remember to add the carried digit to your next column. In this problem, forgetting the carried 1 would give you 72 instead of 82.

Q: Can I add from left to right instead?

It's much harder! Starting from the units place (rightmost) is easier because you immediately know what to carry. Left-to-right addition requires more mental math.

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

Reverse method: Add the numbers in opposite orderSubtraction check: $ 82 - 59 = 23 $Estimation: $ 20 + 60 = 80 $ (close to 82!)

Column Addition with Regrouping

$\begin{aligned} &23 \\ +& \\ &59 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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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 the sum of 2 digits, and then substitute

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

00:09 Place the ones digit, and remember 1 above

00:12 Add tens with tens, remember to add 1 to the calculation

00:19 Place in the tens position

00:23 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

$\begin{aligned} &23 \\ +& \\ &59 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

To solve this problem, we'll use vertical addition and work through each step:

Consider the numbers:

\begin{aligned} &23 \\ +& \\ &59 \\ &\underline{\phantom{776}} \end{aligned}

Step 1: Align the numbers by their place values.
Step 2: Add the units place: $3 + 9 = 12$ . Here, $12$ has two digits. We place $2$ in the units column and carry over $1$ to the tens column.
Step 3: Add the tens place along with the carry: $2 + 5 + 1 = 8$ . Place $8$ in the tens column.

The final sum will be as follows:

\begin{aligned} &23 \\ +& \\ &59 \\ &\underline{\phantom{776}} \\ &82 \end{aligned}

Through these steps, we find that the sum of the numbers $23$ and $59$ is $82$ .

Therefore, the solution to the problem is $82$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Alignment: Stack numbers vertically, matching place values precisely
Technique: Add units first: $3 + 9 = 12$ , write 2 and carry 1
Check: Verify by adding in different order: $59 + 23 = 82$ ✓

Common Mistakes

Avoid these frequent errors

Forgetting to carry the 1 to tens place
Don't just write 12 in the units place = wrong answer of 122! When sum exceeds 9, you must write only the units digit and carry the tens digit. Always carry over when your column sum has two digits.

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 'carry over' mean when adding?

When a column adds up to 10 or more, you write the units digit in that column and carry the tens digit to the next column left. Think of it as borrowing space!

Why do I need to align the numbers vertically?

Aligning by place value ensures you're adding units to units and tens to tens. If numbers aren't aligned, you'll add the wrong digits together!

What if I forget to add the carried number?

You'll get the wrong answer! Always remember to add the carried digit to your next column. In this problem, forgetting the carried 1 would give you 72 instead of 82.

Can I add from left to right instead?

It's much harder! Starting from the units place (rightmost) is easier because you immediately know what to carry. Left-to-right addition requires more mental math.

How do I check if my addition is correct?

Reverse method: Add the numbers in opposite order
Subtraction check: $82 - 59 = 23$
Estimation: $20 + 60 = 80$ (close to 82!)

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