# Problem solving using the column method

## Lesson details

### Key learning points

1. In this lesson, we will learn how to apply our understanding of the column method to finding and fixing errors and completing unfinished column method calculations.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 5 Questions

Q1.
Which equation could be used to estimate the answer to: 653 098 - 118 542?
600 000 - 200 000
Correct answer: 650 000 - 120 000
653 010 - 118 550
653 098 - 118 542
Q2.
Which columns would require regrouping when column subtracting: 563 357 - 325 129?
The digits in the ones and hundreds columns.
The digits in the ones and tens columns.
Correct answer: The digits in the ones and thousands columns.
The digits in the thousands and ten thousands columns.
Q3.
3. Use the column method to calculate the answer to: 561 998 - 138 422 =
123 576
223 576
323 576
Correct answer: 423 576
Q4.
4. Use the column method to calculate the answer to: 183 609 - 21 788 =
Correct answer: 161 821
161 921
162 821
182 921
Q5.
Why might bar modelling be useful?
Bar modelling helps us practise drawing straight lines.
Bar modelling offers us a chance to draw a nice picture to match our maths questions.
Correct answer: Bar modelling offers us a chance to represent equations in a different way which can help us to solve them.
Bar modelling tells us when our answer is incorrect.

## Exit quiz

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### 5 Questions

Q1.
Select the equation below that matches this maths story: '87 315 cars were sold over the weekend. 12 872 of these cars were new and the rest were secondhand. How many cars were secondhand?'
12 872 - 87 315
12 872 + 87 315
Correct answer: 87 315 - 12 872
87 315 + 12 872
Q2.
2. Describe the error that has been made in the following calculation: 213 876 - 114 689 = 328 565.
Regrouping has not taken place correctly in more than one column.
The digits in the columns have not been aligned correctly.
Correct answer: The numbers have been added instead of subtracted.
The numbers have been switched around when subtracting.
Q3.
3. Write out the following column method calculation and describe the error that has occurred: 562 088 - 134 199 = 432 111.
Regrouping has not taken place correctly in more than one column.
The digits in the columns have not been aligned correctly.
The numbers have been added instead of subtracted.
Correct answer: The numbers have been switched around when subtracting.
Q4.
Which of the following methods is NOT a sensible way of checking to see whether we have made an error using the column method?
Check your answer against the estimate to see whether they are similar.
Correct answer: Create a word problem with the numbers that you have used in your calculation.
Recalculate the answer using a different method.
Use the inverse method to confirm your answer.
Q5.
5. What is the missing number in the following equation: 435 629 + _________ = 772 345
236 716
Correct answer: 336 716
436 716
536 716