Starter quiz
- Aisha writes 2684 as approximately 3000. Aisha has written it to the nearest ______.
- 'thousand' ✓
- Which digit is in the ten thousands column in 742 683?
- '4' ✓
- Which digit is in the hundredths column in 129.083?
- '8' ✓
- In the number 3 547 028, which column is the digit 5 in?
- ten millions
- millions
- hundred thousands ✓
- ten thousands
- thousands
-
- In the number 123.4567, which column is the 6 in?
- hundred thousandths
- ten thousandths
- thousandths ✓
- tenths
- thousands
-
- Round each number to the nearest 10.
- 45⇔50 ✓
- 38⇔40 ✓
- 287⇔290 ✓
- 296⇔300 ✓
- 1398⇔1400 ✓
- 1388⇔1390 ✓
Exit quiz
- Truncation is when we simplifying a number by 'cutting off' one or more of the digits and replacing them with ______ if necessary to preserve place value.
- 'zeros' ✓
- The mass of an elephant is 5000 kg when given to the nearest 1000 kg. Which of the following would not be the mass of an elephant?
- 4499.9999999999 kg ✓
- 4500.008 kg
- 4984.2 kg
- 5050.50 kg
- 5500.50 kg ✓
-
- Round 345 678 to the nearest ten thousand.
- '350 000' ✓
- Round 15.0872 to 1 decimal place.
- '15.1' ✓
- Round each of the following to 2 significant figures.
- 0.0108⇔0.011 ✓
- 0.0121⇔0.012 ✓
- 0.0103⇔0.010 ✓
- 10.09987⇔10 ✓
- 11.085⇔11 ✓
- 11.85⇔12 ✓
- Which of the following do not give the same answer when rounded to 2 significant figures or truncated to 2 significant figures?
- 78 426
- 458 500 ✓
- 0.1297 ✓
- 0.010097
- 0.000204503
-
Worksheet
Presentation
Video
Lesson Details
Key learning points
- The first significant figure is the first non-zero digit to have place value.
- Truncation does not consider the digits that follow in the value.
- The loss of accuracy through rounding is not always bad.
Common misconception
When truncating, pupils are tempted to round. Also, when truncating, they cut off the number without thinking about the magnitude.
The use of the place value table shows the magnitude of the number, thus preserving their place value when truncating.
Keywords
Round - Rounding means to change a number into another number that is approximately the same value but is easier to work with.
Degree of accuracy - A degree of accuracy shows how precise a number or measurement is. E.g to the nearest cm, nearest 10, 1 s.f., etc.
Significant figures - Significant figures are the digits in a number that contribute to the accuracy of the number. The first significant figure is the first non-zero digit.
Truncation - Truncation is when we simplifying a number by 'cutting off' one or more of the digits and replacing them with zeros if necessary to preserve place value.