When we add digits in a column and the result is 10 or more, we cannot write a two-digit number in a single column. So we write the units digit below the line and carry the tens digit forward to the next column on the left. This is called carrying (also called regrouping).
7 + 5Column sum= 12 (10 or more)
carry 1Tens digit → next columnWrite 1 above next column
2Units digit → below lineWrite 2 in answer row
The carry is always 1. Because we are adding single digits (0–9) to single digits, the maximum any column can reach is 9 + 9 = 18, so the tens digit carried is always just 1. It can never be 2 or more at this level.
▶ Column Method — Steps (With Carry)
Set up the column exactly as before: larger number on top, align H under H, T under T, O under O.
Add the Ones column. If the sum is ≤ 9 — write it below the line normally. If the sum is ≥ 10 — write the units digit below the line and write a small 1 above the Tens column.
Add the Tens column — including the carried 1 if present. Again, if ≥ 10, write units digit below and carry 1 to Hundreds.
Add the Hundreds column — including any carry. Write the full result below the line.
Draw the double line. Read the answer.
⚠ Most Common Mistakes
1. Forgetting to add the carried 1 to the next column. 2. Writing the full two-digit sum (e.g. writing "12" in the Ones column instead of writing "2" and carrying "1"). 3. Misplacing the carry — it must go above the next column to the left, not the current one.
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Concept 2 — Adding 2-Digit Numbers With Carry
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With 2-digit numbers, the carry happens when the Ones column adds up to 10 or more. The carried 1 is added into the Tens column.
Q4True or False: In 64 + 29, the Ones column gives 4+9=13, so we write 13 below the line. Correct it if false.▼
AnswerFalse. We never write two digits in one column.
4 + 9 = 13 → write only 3 below the line, and carry 1 to the Tens column.
Correct working: T: 6+2+1 = 9. Answer: 93.
With 3-digit numbers, a carry can happen in the Ones column, the Tens column, or both. Each carry is handled the same way — write the units digit, pass the 1 to the next column.
Q9Rohan solves 486 + 357 and writes 833. Check his answer. Is he right?▼
Answer
HTO
11·
486
+357
843
O: 6+7=13 → 3, carry 1. T: 8+5+1=14 → 4, carry 1. H: 4+3+1=8. Correct answer = 843. No, Rohan is wrong. He likely forgot the carry in the Tens column. Correct answer is 843.
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Concept 4 — Word Problems
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Word problems involving carry are solved the same way as before — read, identify numbers, check for carry, solve with column method, write the answer in a sentence.
▶ Solved Example 8 — 2-Digit
A toy shop sold 48 cars and 37 trains in one day. How many toys were sold in all?
TO
1·
48
+37
85
O
8 + 7 = 15 → write 5, carry 1.
T
4 + 3 + 1 = 8.
85 toys were sold in all.
▶ Solved Example 9 — 3-Digit
A school collected 458 notebooks in Class 2 and 375 notebooks in Class 3. What is the total number of notebooks collected?
HTO
11·
458
+375
833
O
8 + 5 = 13 → write 3, carry 1.
T
5 + 7 + 1 = 13 → write 3, carry 1.
H
4 + 3 + 1 = 8.
The total number of notebooks collected is 833.
✍ Practice — Concept 4
Q10A farmer harvested 265 kg of wheat and 348 kg of rice. Find the total harvest.▼
Answer
HTO
11·
265
+348
613
O: 5+8=13 → 3, carry 1. T: 6+4+1=11 → 1, carry 1. H: 2+3+1=6. Total = 613 kg.
Q11There are 476 boys and 389 girls in a school. How many students are there in all?▼
Q2Solve using the column method showing all carries: 469 + 354▼
Answer
HTO
11·
469
+354
823
O
9+4=13 → 3, carry 1
T
6+5+1=12 → 2, carry 1
H
4+3+1=8
469 + 354 = 823
Q3A student solves 374 + 458 = 722. Find the correct answer. What mistake did the student make?▼
Answer
HTO
11·
374
+458
832
Correct answer = 832.
The student wrote 722 — meaning they got H as 7 instead of 8. They added 3+4=7 but forgot to add the carry 1 from the Tens column.
Q4In a city, 648 buses and 579 trains run every day. Find the total number of vehicles using the column method.▼
Q5Fill in the missing digit: 3_7 + 245 = 652. Find the missing Tens digit using the column method.▼
Answer
Let the missing Tens digit = a.
O: 7 + 5 = 12 → write 2, carry 1. ✓ (Answer Ones = 2 ✓)
T: a + 4 + 1(carry) = 5 (answer Tens digit) → a + 5 = 5 → a = 0
H: 3 + 2 = 5 → write 5. ✓ (Answer Hundreds = 6? — wait, H = 3+2=5 but answer H = 6.) If H of answer = 6, then T column must produce a carry too. Let us re-check:
T: a + 4 + 1 = 15 → means we need a carry from T to H. So a + 5 = 15 → impossible for single digit. Try a + 5 = 5 (no carry) → H = 3+2=5 ≠ 6. Try T producing carry: a + 5 ≥ 10 → a ≥ 5. If a=5: T = 5+5=10 → write 0, carry 1 → H = 3+2+1 = 6 ✓.
So a = 5. The missing Tens digit is 5.
HTO
11·
357
+245
602
Note: 357 + 245 = 602, not 652. The original question has a typo — but the method of working backwards through carries is the key skill being tested.
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📄 Free Worksheet
Practise 2-digit and 3-digit addition with carry using the column method, including word problems and error-checking questions. No login required.