Starter quiz
- Which of the following is not an integer?
- −3249
- 10 904
- 12 348.4839 ✓
- 34 839.48 ✓
- 439 043 904
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- State the smallest and largest integers that round to 520 when rounded to the nearest 10.
- Smallest integer = 514, largest integer = 525
- Smallest integer = 514, largest integer = 524
- Smallest integer = 515, largest integer = 525
- Smallest integer = 515, largest integer = 524 ✓
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- State the smallest and largest integers that round to 3900 when rounded to the nearest 100.
- Smallest integer = 3849, largest integer = 3949
- Smallest integer = 3850, largest integer = 3949 ✓
- Smallest integer = 3850, largest integer = 3950
- Smallest integer = 3855, largest integer = 3950
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- When does 0.4999999 NOT round to give 0.5?
- When rounded to the nearest integer. ✓
- When rounded to 1 significant figure.
- When rounded to 1 decimal place.
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- Work out 3.4 km + 348 m + 6000 cm. Give your answer in metres.
- 3808 m ✓
- 380.8 m
- 38.08 m
- 4 348 m
- 434.8 m
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- Work out 0.05 km + 6.32 m + 123 cm. Give your answer in centimetres.
- 80.5 cm
- 805 cm
- 1255 cm
- 5755 cm ✓
- 12 550 cm
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Exit quiz
- An error interval for a number shows the range of possible values of . It is written as:
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- ✓
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- When a number is rounded to the nearest integer the result is 8. Identify the correct range for the unrounded number.
- Smallest = , Largest = ✓
- Smallest = , Largest =
- Smallest = , Largest =
- Smallest = , Largest =
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- When a number is rounded to the nearest integer the result is 19. Identify the correct range for the unrounded number.
- Smallest = , Largest =
- Smallest = , Largest = ✓
- Smallest = , Largest =
- Smallest = , Largest =
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- When a number, , is rounded to the nearest integer the result is 8. Identify the error interval for .
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- ✓
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- When a number, , is rounded to 2 significant figures the result is 7.8. Identify the error interval for .
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- ✓
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- A distance km is given as 2.345 km correct to the nearest metre. Identify the error interval for .
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- ✓
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Worksheet
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Presentation
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Lesson Details
Key learning points
- When given a rounded number you can say what the biggest and smallest values of the unrounded number could have been.
- You can use notation to express the range of values the unrounded number could have taken.
Common misconception
Incorrect use of the error interval i.e or writing the error interval as
As a check, encourage students to round the upper limit interval by the degree of accuracy to see if it evaluates to the rounded number. Also, draw a number line to show the meaning of and allow students to see the error.
Keywords
Range - A range of values where every value in the range estimates to the given value.
Error interval - An error interval for a number shows the range of possible values of . It is written as an inequality
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