Solve Vertical Addition: 72 + 7 Step by Step

Q: Where do I put the 7 when adding to 72?

Always place the 7 under the 2 (in the ones column). Think of 7 as having an invisible zero in the tens place, so it's really 07.

Q: Do I need to carry anything in this problem?

No carrying needed! Since 2 + 7 = 9, which is less than 10, we simply write 9 in the ones place and keep the 7 in the tens place.

Q: How can I check if 79 is correct?

Try counting up from 72: 73, 74, 75, 76, 77, 78, 79. That's 7 jumps, so $ 72 + 7 = 79 $ is right!

Q: What if I accidentally got 142?

You probably put 7 in the wrong column! Remember: 7 goes under the 2, not under the 7. This mistake turns the problem into 72 + 70 instead of 72 + 7.

Q: Is there a faster way than vertical addition?

For small numbers like this, you can think: "72 plus 7 more" and count up. But vertical addition helps you organize your work and avoid mistakes with larger numbers.

Vertical Addition with Two-Digit Numbers

$\begin{aligned} &72 \\ +& \\ &~~7 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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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 combining 2 digits, and then we'll place

00:06 we'll start by combining ones with ones, we'll place the solution

00:09 we'll place 0 where there is no digit

00:12 we'll combine tens with tens, we'll place the solution

00:15 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

$\begin{aligned} &72 \\ +& \\ &~~7 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

Step-by-step solution

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

Step 1: Align the numbers such that the units are directly under each other:

$\begin{array}{r} 72 \\ + 7 \\ \hline \end{array}$

Step 2: Add the units column. The units are 2 and 7.

Calculation: $2 + 7 = 9$ . The result for the units column is 9.

Step 3: Add the tens column. The tens are 7 with no carry from the previous step.

Calculation: $7 + 0 = 7$ . The result for the tens column remains 7.

Step 4: Combine both results:

Therefore, the sum is $79$ .

Hence, the final answer is $79$ . The correct choice is option 3.

Final Answer

Key Points to Remember

Essential concepts to master this topic

Alignment: Place ones under ones, tens under tens vertically
Technique: Add 2 + 7 = 9 in ones column first
Check: Count up from 72: 73, 74, 75, 76, 77, 78, 79 ✓

Common Mistakes

Avoid these frequent errors

Misaligning the single digit number
Don't place the 7 under the tens column like 72 + 70 = 142! This treats 7 as 70 instead of 7. Always align single digits under the ones column on the right.

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

Where do I put the 7 when adding to 72?

Always place the 7 under the 2 (in the ones column). Think of 7 as having an invisible zero in the tens place, so it's really 07.

Do I need to carry anything in this problem?

No carrying needed! Since 2 + 7 = 9, which is less than 10, we simply write 9 in the ones place and keep the 7 in the tens place.

How can I check if 79 is correct?

Try counting up from 72: 73, 74, 75, 76, 77, 78, 79. That's 7 jumps, so $72 + 7 = 79$ is right!

What if I accidentally got 142?

You probably put 7 in the wrong column! Remember: 7 goes under the 2, not under the 7. This mistake turns the problem into 72 + 70 instead of 72 + 7.

Is there a faster way than vertical addition?

For small numbers like this, you can think: "72 plus 7 more" and count up. But vertical addition helps you organize your work and avoid mistakes with larger numbers.

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