Starter quiz
Where will regrouping be needed in this column addition?- In the tens only ✓
- In the ones only
- In the tens and the ones
- Regrouping will not be needed
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What is the missing sum?- '191' ✓
What is the missing digit in this column addition?- '7' ✓
- What would be a good estimate for the sum of 189 + 217?
- 200
- 300
- 400 ✓
- 500
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- Which of these calculations would it be more efficient to calculate mentally?
- 99 + 255 ✓
- 258 + 367
- 220 + 440 ✓
- 565 + 259
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- Which pairs of addends give a sum between 500 and 600?
- 317 + 315
- 367 + 204 ✓
- 489 + 99 ✓
- 505 + 103
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Exit quiz
- Each of Enzo the elephant’s tusks are 315 cm long. Which would be the most accurate estimate for the length of both of his tusks?
- 500 cm
- 600 cm ✓
- 700 cm
- 800 cm
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- Each of Enzo the elephant’s tusks are 315 cm long. What is the total length of both of his tusks? ______ cm.
- '630' ✓
Eddie the elephant is 347 cm tall. With his trunk, he can reach an extra 148 cm upwards. How far can he reach altogether? Eddie can reach ______ cm.- '495 ' ✓
- Which calculation is the best one to estimate the sum of 459 + 289?
- 400 + 200
- 400 + 300
- 450 + 300 ✓
- 500 + 300
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Look carefully at Alex’s column addition. Which of these statements about the sum is true?- The ones digit is incorrect.
- The tens digit is incorrect.
- The hundreds digit is incorrect. ✓
- The sum is correct.
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Eva and baby Elliott have a total length of 585 cm. Choose the correct lengths for Eva and her baby.- Eva is 399 cm long.
- Eva is 389 cm long. ✓
- Baby Elliott is 196 cm long. ✓
- Baby Elliott is 176 cm long.
- Baby Elliott is 156 cm long.
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Worksheet
Presentation
Video
Lesson Details
Key learning points
- Estimation gives you a value close to the correct answer.
- Start with the digits with the smallest place value so that regrouping can be represented.
- Look carefully at the ones number of the sum to find missing addends.
Common misconception
Pupils may not make very accurate estimates for their calculations.
This lesson explores inaccurate estimations. Estimations should be quick and easy to calculate, but when adding two addends, it's sensible to make one larger and one smaller so that the estimate is as accurate as possible.
Keywords
Estimate - Estimation means to find a value that is close enough to the right answer, usually with some thought or calculation involved.
Regroup - The process of unitising and exchanging between place values is known as regrouping.
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