Column addition and subtraction

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Notes de leçon

What is Column Addition?

Column addition is a way to add numbers by writing them one under the other, lining up the digits by place value (ones, tens, hundreds, thousands).
Always start adding from the rightmost column (the ones column) and move left.
Carrying (also called regrouping) happens when a column adds up to 10 or more. You write the ones digit and carry the tens digit to the next column on the left.
Example: 27 + 59. Add 7 + 9 = 16. Write 6 in the ones column and carry 1 to the tens column. Then add 2 + 5 + 1 = 8. So 27 + 59 = 86.
You can add numbers with up to 4 digits using this method, like 3456 + 2789.

What is Column Subtraction?

Column subtraction is a way to subtract numbers by writing them one under the other, lining up the digits by place value.
Start from the rightmost column (ones) and move left.
Borrowing (also called exchanging) is needed when the top digit is smaller than the bottom digit in a column.
To borrow, you take 1 from the next column to the left, making it 10 in the current column. Then subtract.
Example: 47 - 19. In the ones column, 7 - 9 is too small, so borrow 1 from the tens. The 4 becomes 3, and the 7 becomes 17. 17 - 9 = 8. Then 3 - 1 = 2. So 47 - 19 = 28.
You can subtract numbers with up to 4 digits using this method, like 5000 - 2345.

Estimating Answers

Before you calculate, it is a good idea to estimate the answer. This helps you check if your final answer is sensible.
To estimate, round each number to the nearest ten, hundred, or thousand, then do the calculation with the rounded numbers.
For example, to estimate 3456 + 2789, round to the nearest thousand: 3000 + 3000 = 6000. The real answer is close to 6000.
For subtraction, estimate like this: 5000 - 2345 ≈ 5000 - 2000 = 3000.
Estimating gives you a rough idea, not the exact answer.

Checking with the Inverse Operation

You can check your answer using the inverse operation. Addition and subtraction are opposites.
If you added two numbers, subtract one of them from your answer. You should get the other number.
Example: 27 + 59 = 86. Check: 86 - 59 = 27. ✔
If you subtracted, add the number you subtracted to your answer. You should get the starting number.
Example: 47 - 19 = 28. Check: 28 + 19 = 47. ✔
Always check your work to catch mistakes.

Choosing a Method

Sometimes you can add or subtract mentally (in your head) without writing columns.
Use mental math for easy numbers, like 20 + 30 or 100 - 40.
Use column method for bigger numbers or when you need to carry or borrow.
If you are not sure, you can always use the column method – it works for any numbers.
Practice both ways so you can choose the quickest.

Solving Word Problems

Word problems tell a story and ask a question. You need to find the numbers and decide what to do.
Look for key words that hint at addition: 'in all', 'total', 'together', 'more than'.
Look for key words that hint at subtraction: 'difference', 'left', 'fewer than', 'take away'.
Some problems need two steps: you might add first, then subtract, or vice versa.
Example: 'Sara has 125 stickers. She gets 80 more. Then she gives 45 away. How many does she have left?' First add 125 + 80 = 205, then subtract 45: 205 - 45 = 160.
Always read the problem carefully and underline the question.

Common Mistakes to Avoid

Always line up the digits by place value. If you don't, your answer will be wrong.
Don't forget to carry when a column adds to 10 or more.
Don't forget to borrow when the top digit is smaller than the bottom digit.
When borrowing, remember to reduce the digit you borrowed from by 1.
Check your work with estimation or the inverse operation.

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1.What is the digit that is transferred from one column to the next when adding numbers called?
Easy
- Acarry
- Bborrow
- Cregroup
- Dexchange
2.In subtraction, the operation of taking a ten from the next column is called a borrow.
Easy
True or false?
3.Which of the following is the correct way to check that 456 + 389 = 845?
Medium
- ASubtract 389 from 845 to see if you get 456
- BAdd 456 and 389 again
- CMultiply 456 by 2
- DSubtract 456 from 389
4.Which of the following sums require carrying (regrouping) when using the column method? (Select all that apply)
Medium
- A23 + 45
- B56 + 37
- C128 + 254
- D345 + 210
- E999 + 1
5.When adding 27 and 59, the carry from the ones column is 1.
Easy
True or false?
6.Match each calculation with the correct answer.
Easy
- 345 + 278
- 504 - 267
- 1234 + 5678
- 623
- 237
- 6912
7.Put the steps for column addition of 27 and 59 in the correct order.
Medium
- Add the ones: 7+9=16, write 6 and carry 1
- Add the tens: 1+2+5=8
- Write the 8 in the tens column
- Write the 6 in the ones column
8.Which of the following calculations require borrowing (exchanging) when using column subtraction? (Select all that apply)
Medium
- A52 - 18
- B63 - 21
- C400 - 156
- D78 - 34

Plus de questions

9.When adding 456 and 389, you carry a 1 from the ones column to the tens column.
Easy
True or false?
10.A shop has 2500 pencils. It sells 1347 pencils. How many pencils are left?
Medium
- A1153
- B1157
- C1253
- D1143
11.Put the steps for column subtraction of 504 - 267 in the correct order.
Medium
- Subtract the ones: 4 - 7, borrow 1 ten from the tens column
- Now subtract the ones: 14 - 7 = 7
- Borrow from the hundreds column to the tens column
- Subtract the tens: 0 - 6 becomes 9 - 6 = 3
- Subtract the hundreds: 4 - 2 = 2
12.In addition, what is the digit that is moved to the next column called?
Easy
- Acarry
- Bborrow
- Csum
- Dregroup
13.In subtraction, the operation of taking a ten from the next column is called a carry.
Easy
True or false?
14.When adding 456 and 389 using column addition, what is the first step?
Easy
- AAdd the hundreds column: 4 + 3 = 7
- BAdd the ones column: 6 + 9 = 15
- CAdd the tens column: 5 + 8 = 13
- DEstimate the answer first
15.When subtracting 47 - 19 using column subtraction, what happens in the ones column?
Easy
- A7 - 9 = -2, so we borrow 1 from the tens column
- B7 - 9 = 2, so we write 2
- CWe add 10 to 7 to get 17, then subtract 9
- DWe subtract 7 from 9 to get 2
16.Which of the following calculations require carrying (regrouping) when using column addition? (Select all that apply)
Medium
- A27 + 59
- B34 + 25
- C156 + 278
- D123 + 456
17.When adding 3456 and 2789, what is the carry from the tens column?
Medium
- A1
- B2
- C3
- D0
18.When subtracting 504 - 267, what is the first step in the ones column?
Medium
- A4 - 7 = -3, so borrow from the tens column
- B4 - 7 = 3, write 3
- C14 - 7 = 7, write 7
- D7 - 4 = 3, write 3
19.In column subtraction, you always start with the hundreds column.
Easy
True or false?
20.A school has 2345 students. Another school has 1987 students. How many more students does the first school have?
Medium
- A358
- B368
- C468
21.When adding 678 and 345, what is the carry from the ones column?
Medium
- A1
- B2
- C3
- D0
22.The answer to a subtraction problem is called the difference.
Easy
True or false?
23.Which of the following calculations require borrowing when using column subtraction? (Select all that apply)
Medium
- A500 - 123
- B456 - 234
- C800 - 567
- D321 - 210
24.Put the steps for column addition of 456 and 389 in the correct order.
Medium
- Add the ones column: 6 + 9 = 15, write 5 and carry 1.
- Add the tens column: 5 + 8 + 1 = 14, write 4 and carry 1.
- Add the hundreds column: 4 + 3 + 1 = 8, write 8.
- Write the numbers in columns, aligning units, tens, and hundreds.
25.Which calculation gives the largest answer?
Medium
- A345 + 678
- B456 + 567
- C234 + 789
- D123 + 890
26.When adding 567 and 289, you carry a 1 from the ones column to the tens column.
Easy
True or false?
27.Put the steps for column addition of 348 and 276 in the correct order.
Medium
- Add the ones: 8+6=14, write 4, carry 1
- Add the tens: 4+7+1=12, write 2, carry 1
- Add the hundreds: 3+2+1=6, write 6
- Write the answer as 624
28.Match each calculation with its correct answer.
Medium
- 345 + 267
- 500 - 123
- 678 + 234
- 612
- 377
- 912
29.A rectangle has a length of 245 cm and a width of 178 cm. What is the perimeter of the rectangle?
Hard
- A423 cm
- B846 cm
- C67 cm
- D323 cm
30.What is the digit that is transferred from one column to another when adding numbers called?
Easy
- Acarry
- Bborrow
- Csum
- Ddifference
31.When adding 27 and 59, what is the carry from the ones column?
Easy
- A0
- B1
- C2
- D10
32.Match each addition problem with its correct sum.
Easy
- 27 + 59
- 345 + 278
- 456 + 389
- 623
- 845
- 86
33.Put the steps for column addition of 345 and 278 in the correct order.
Medium
- Add the hundreds: 3 + 2 plus any carry from the tens.
- Add the ones: 5 + 8 = 13. Write 3, carry 1 to the tens.
- Add the tens: 4 + 7 plus the carry 1 = 12. Write 2, carry 1 to the hundreds.
- Write the numbers one under the other, lining up the ones, tens and hundreds.
34.Which of the following subtraction problems require borrowing (exchanging) when using column subtraction? (Select all that apply)
Medium
- A504 - 267
- B93 - 51
- C400 - 156
- D78 - 34
35.What is the correct sum of 456 and 389?
Medium
- A835
- B845
- C745
- D855
36.What is the correct difference of 1000 - 456?
Medium
- A544
- B554
- C444
- D644
37.When adding 27 and 59, the sum of the ones column is 16.
Easy
True or false?
38.When subtracting 47 - 19, you need to borrow from the tens column.
Easy
True or false?
39.Match each addition calculation with its correct sum.
Medium
- 234 + 567
- 789 + 456
- 1234 + 5678
- 801
- 1245
- 6912
40.A bakery makes 1,250 loaves of bread on Monday and 1,375 loaves on Tuesday. How many loaves did it make in total?
Medium
- A2,625
- B2,525
- C2,615
- D2,725
41.Complete the sentence: When adding 27 and 59, first add 7 and 9 to get 16. Write the 6 in the ones column and carry the ___ to the tens column.
Easy
When adding 27 and 59, first add 7 and 9 to get 16. Write the 6 in the ones column and carry the ____ to the tens column.
42.Use column addition to find the sum of 345 and 278.
Easy
43.Use column subtraction to find 504 - 267.
Medium
44.There are 1245 books in the library. The school buys 678 more books. How many books are there now?
Medium
45.A farmer has 3000 apples. He sells 1243 apples. How many apples are left?
Medium
46.In the addition 27 + 59, the sum of the ones column is 16. Write the 6 in the ones column and carry the ___ to the tens column.
Easy
In the addition 27 + 59, the sum of the ones column is 16. Write the 6 in the ones column and carry the ____ to the tens column.
47.What is the name of the operation used in subtraction when you take a ten from the next column?
Easy
48.What is the sum of 3456 and 2789?
Medium
49.Complete the sentence about column subtraction.
Easy
When subtracting 47 - 19, first subtract 7 - 9. Since 7 is less than 9, you ____ 1 ten from the tens column.
50.What is the name of the digit that is carried to the next column when adding?
Medium
51.Complete the sentence.
Easy
When adding 27 and 59, first add 7 and 9 to get 16. Write the 6 in the ones column and carry the ____ to the tens column.
52.A shop sells 1567 bottles in the morning and 2345 bottles in the afternoon. How many bottles were sold in total?
Medium
53.Explain why you need to borrow when subtracting 400 - 156, and then find the answer.
Hard
54.Describe the steps to add 456 and 389 using column addition, and explain what happens when a column adds to more than 9.
Hard
55.Explain how to check the subtraction 504 - 267 = 237 using addition.
Hard
56.Explain how to check the subtraction 1000 - 456 = 544 using addition.
Hard
57.Use column addition to find the sum of 345 and 278.
Easy
- A685
- B747
- C561
- D623
58.Use column subtraction to find 504 - 267.
Medium
- A237
- B213
- C285
- D261
59.There are 1245 books in the library. The school buys 678 more books. How many books are there now?
Medium
- A1731 books
- B2307 books
- C2115 books
- D1923 books
60.A farmer has 3000 apples. He sells 1243 apples. How many apples are left?
Medium
- A1757 apples
- B1933 apples
- C1581 apples
- D2109 apples
61.What is the sum of 3456 and 2789?
Medium
- A5620
- B7495
- C6245
- D6870
62.A shop sells 1567 bottles in the morning and 2345 bottles in the afternoon. How many bottles were sold in total?
Medium
- A4303 bottles
- B3912 bottles
- C4694 bottles
- D3521 bottles

Notes de révision

## Column Addition and Subtraction When you add or subtract big numbers, use **column addition** and **column subtraction**. Write the numbers in columns: ones, tens, hundreds, thousands. ### Addition with Carrying Sometimes a column adds to 10 or more. Then you **carry** the extra ten to the next column on the left. **Example:** 27 + 59 ``` 1 27 + 59 ---- 86 ``` - Add the ones: 7 + 9 = 16. Write 6 in the ones column and carry the 1 to the tens column. - Add the tens: 1 (carried) + 2 + 5 = 8. Write 8 in the tens column. - Answer: 86. ### Subtraction with Borrowing Sometimes the top digit is smaller than the bottom digit. Then you **borrow** 1 ten from the next column on the left. That ten becomes 10 ones. **Example:** 47 − 19 ``` -1 47 − 19 ---- 28 ``` - Ones: 7 − 9 is too small, so borrow 1 ten from the 4. The 4 becomes 3, and the 7 becomes 17. Now 17 − 9 = 8. - Tens: 3 − 1 = 2. - Answer: 28. ### Estimating and Checking Before you calculate, **estimate** the answer by rounding. After you calculate, **check** your answer using the **inverse operation**. For addition, use subtraction to check. For subtraction, use addition to check. **Example:** 345 + 278 ≈ 300 + 300 = 600 (estimate). Calculate: 345 + 278 = 623. Check: 623 − 278 = 345. ✓ ### Choosing a Method Sometimes you can do the calculation in your head, especially with easy numbers. For harder numbers, use the column method. ### Word Problems Read the problem carefully. Decide if you need to add or subtract. Look for clue words: "in all", "total", "altogether" often mean addition. "How many more", "how many left", "difference" often mean subtraction. **Example:** A shop has 125 red balloons and 89 blue balloons. How many balloons in all? 125 + 89 = 214 balloons. **Example:** A book has 250 pages. You read 178 pages. How many pages are left? 250 − 178 = 72 pages. ### Key Rules - Always line up digits by place value. - Start from the right (ones). - Carry when a sum is 10 or more. - Borrow when a top digit is too small. - Estimate first, then check with the inverse.

column addition: A way to add numbers by writing them in columns (ones, tens, hundreds) and adding each column from right to left.
column subtraction: A way to subtract numbers by writing them in columns and subtracting each column from right to left.
carry: When adding, if a column adds to 10 or more, you write the ones digit and carry the tens digit to the next column on the left.
borrow: When subtracting, if the top digit is smaller than the bottom digit, you borrow 1 ten from the next column on the left, making it 10 ones.
estimate: To find an approximate answer by rounding numbers before calculating.
inverse operation: The opposite operation. Addition and subtraction are inverse operations. Use one to check the other.

Cartes mémo

What is a 'carry' in column addition?

A carry is a digit moved from one column to the next column on the left. For example, when you add 6 and 7, you get 13. You write the 3 in the ones column and carry the 1 to the tens column.

What is a 'borrow' in column subtraction?

A borrow is when you take 1 from the next column to the left because the top digit is too small to subtract. For example, in 47 - 19, you cannot subtract 9 from 7, so you borrow 1 ten from the 4, making it 3 tens and 17 ones.

When adding 27 + 59 using columns, what happens in the ones column?

7 + 9 = 16. Write 6 in the ones column and carry 1 to the tens column.

When adding 27 + 59 using columns, what happens in the tens column?

Add the carried 1 to 2 and 5: 1 + 2 + 5 = 8. Write 8 in the tens column. The answer is 86.

What is the first step in column addition?

Write the numbers one under the other, lining up the ones, tens, hundreds, and thousands. Then add the ones column first.

Why do we start adding from the rightmost column?

Because when a column adds to 10 or more, we need to carry to the next column on the left. Starting from the right makes it easy to carry.

What does 'regrouping' mean in addition?

Regrouping is another name for carrying. When a column adds to 10 or more, you regroup 10 ones as 1 ten, or 10 tens as 1 hundred, and so on.

What does 'exchanging' mean in subtraction?

Exchanging is another name for borrowing. When the top digit is smaller than the bottom digit, you exchange 1 from the next column for 10 in the current column.

How do you check an addition answer?

Use the inverse operation: subtraction. For example, if 27 + 59 = 86, then check 86 - 59 = 27.

How do you check a subtraction answer?

Use the inverse operation: addition. For example, if 47 - 19 = 28, then check 28 + 19 = 47.

What is an estimate?

An estimate is a close guess. Before adding or subtracting, you can round the numbers to the nearest ten or hundred to get an approximate answer.

Estimate 347 + 482 by rounding to the nearest hundred.

347 rounds to 300, 482 rounds to 500. So the estimate is 300 + 500 = 800.

Estimate 623 - 189 by rounding to the nearest ten.

623 rounds to 620, 189 rounds to 190. So the estimate is 620 - 190 = 430.

When should you use mental math instead of column method?

When the numbers are small or easy to compute in your head, like 30 + 40 or 100 - 20. For larger numbers, use the column method.

What is a one-step word problem?

A word problem that requires only one operation, either addition or subtraction. For example: 'Tom has 45 stickers. He gets 23 more. How many does he have?'

What is a two-step word problem?

A word problem that requires two operations, like adding then subtracting. For example: 'Sara has 100 marbles. She gives 30 to her friend and then finds 15. How many does she have now?'

In the problem 'There are 256 boys and 189 girls in a school. How many students are there?', what operation do you use?

Addition, because you are combining the number of boys and girls. 256 + 189 = 445.

In the problem 'A shop has 500 apples. It sells 275. How many are left?', what operation do you use?

Subtraction, because you are taking away the sold apples. 500 - 275 = 225.

What is the 'inverse operation'?

The opposite operation. Addition and subtraction are inverses. Addition undoes subtraction, and subtraction undoes addition.

When adding 999 + 1 using columns, what happens?

9 + 1 = 10, so write 0 and carry 1. Then 9 + 1 = 10 again, write 0 and carry 1. Then 9 + 1 = 10, write 0 and carry 1. The answer is 1000.

When subtracting 1000 - 1 using columns, what happens?

You need to borrow from the thousands column. 1000 becomes 999 + 1, so 1000 - 1 = 999.

What is the 'carry' in the addition of 6 and 7?

The carry is 1, because 6 + 7 = 13. The 1 is carried to the tens column.

What is the 'borrow' in the subtraction 47 - 19?

You borrow 1 ten from the 4 in the tens column, making it 3 tens and 17 ones. Then 17 - 9 = 8, and 3 - 1 = 2, so the answer is 28.

Why is it important to line up the digits correctly?

So that you add or subtract ones with ones, tens with tens, and so on. If you don't line them up, you get the wrong answer.

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