Solve Three-Digit Addition: 791 + 145 in Vertical Format

Three-Digit Addition with Column Carrying

791+145776 \begin{aligned} &791 \\ +& \\ &145 \\ &\underline{\phantom{776}} & \\ \end{aligned}

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1

Understand the problem

791+145776 \begin{aligned} &791 \\ +& \\ &145 \\ &\underline{\phantom{776}} & \\ \end{aligned}

2

Step-by-step solution

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

  • Step 1: Properly align the two numbers 791 and 145 vertically by their place values.

  • Step 2: Add the digits column by column, starting from the rightmost column (units position).

  • Step 3: Apply carrying over when the sum of any column exceeds 9.

Now, let's work through each step:

Step 1: Arrange the numbers:

791+145 \begin{array}{c} & 7 & 9 & 1 \\ + & 1 & 4 & 5 \\ \hline \end{array}

Notice the digits are aligned correctly according to their place value.

Step 2: Start adding from the rightmost column:

  • Units column: 1+5=61 + 5 = 6. Write 6 in the units place.

  • Tens column: 9+4=139 + 4 = 13. Write 3 in the tens place and carry over 1 to the hundreds place.

  • Hundreds column: 7+1=87 + 1 = 8, plus the carry over 1 gives 8+1=98 + 1 = 9. Write 9 in the hundreds place.

Step 3: The final result is:

936 \begin{array}{c} & & 9 & 3 & 6 \\ \end{array}

Therefore, the sum of 791 and 145 is 936\textbf{936}.

3

Final Answer

936

Key Points to Remember

Essential concepts to master this topic
  • Alignment: Stack numbers by place value with units column aligned
  • Technique: Add column by column: 1+5=6, 9+4=13 (write 3, carry 1)
  • Check: Verify by adding in reverse: 936 - 145 = 791 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to carry over when column sum exceeds 9
    Don't write 13 in the tens place when 9+4=13 = wrong answer 1336! The tens column can only hold single digits. Always write the units digit (3) and carry the tens digit (1) 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 over' mean in addition?

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When adding a column gives you more than 9, you write down the ones digit and 'carry' the tens digit to the next column. For example, 9+4=13 9 + 4 = 13 , so write 3 and carry the 1.

Why do I need to align the numbers vertically?

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Place value alignment is crucial! Units must line up with units, tens with tens, and hundreds with hundreds. This ensures you're adding the correct digits together.

What if I forget to add the carried number?

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You'll get the wrong answer! In this problem, if you forget to add the carried 1 to the hundreds column, you'd get 836 instead of 936. Always remember to include carried digits.

How can I check if my addition is correct?

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Use subtraction to verify: Take your answer and subtract one of the original numbers. You should get the other original number. For example: 936145=791 936 - 145 = 791

What if both numbers have different amounts of digits?

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No problem! Just align them by place value. If adding a 2-digit and 3-digit number, the empty hundreds place in the 2-digit number is treated as zero.

Can I add from left to right instead?

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It's much harder! Adding from right to left (ones, then tens, then hundreds) makes carrying easier to track and reduces mistakes. Stick with this method!

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