New
New
Year 8

Rounding integers to one significant figure

I can round integers to one significant figure.

New
New
Year 8

Rounding integers to one significant figure

I can round integers to one significant figure.

Lesson details

Key learning points

  1. It is possible to use rounding and place value to know the size of a number without knowing the actual number.
  2. The first non-zero digit of a number is the first significant figure.
  3. You can identify the place value of the first significant figure.
  4. A number can be located on a number line and numbers to 1 significant figure either side of it represented.
  5. Any integer can be rounded to one significant figure and a number line can help with this.

Common misconception

Assuming all zero digits are not significant.

Within the lesson there are many examples where some zeros are significant. Relate significance back to the communication of accuracy and that some digits are significant as they preserve the place value of other digits.

Keywords

  • Significant figure - 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.

  • Round - To change a number into another number that is approximately the same value but is easier to work with. E.g. round 561 to the nearest 10 is 560.

Pupils could come up with their own coded words or messages using the grid in the 3rd learning cycle. This will give pupils the opportunity to embed their understanding of significant figures. They can then swap and decode each others words or messages.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
A degree of shows how precise a number or measurement is. Examples are: to the nearest cm, to the nearest 10, to 1 s.f. and 2 d.p.
Correct Answer: accuracy
Q2.
Round 15.076 to two decimal places.
Correct Answer: 15.08
Q3.
Round 0.0504 to one decimal place.
Correct Answer: 0.1
Q4.
Round 20.961 to 1 decimal place.
Correct Answer: 21.0
Q5.
Calculate the cost of carpeting this area.
An image in a quiz
Correct Answer: £76.73, 76.73
Q6.
3 friends go out for lunch and spend £31. They pay the same amount each. What is the smallest amount they each pay to cover the cost of the bill?
Correct Answer: £10.34, 10.34

6 Questions

Q1.
The first significant figure is the first non- digit in a number.
Correct Answer: zero, 0
Q2.
Select all the numbers which have 4 as the first significant figure.
Correct answer: 4698
54 875
Correct answer: 403 146
644 145
Correct answer: 4 002 231
Q3.
In the number 654 023, in which column is the first significant figure?
tens
hundreds
thousands
ten thousands
Correct answer: hundred thousands
Q4.
Match each number to its value when it is rounded to one significant figure.
Correct Answer:4 564 231,five million

five million

Correct Answer:52.96,fifty

fifty

Correct Answer:48 264,fifty thousand

fifty thousand

Correct Answer:5365.12,five thousand

five thousand

Correct Answer:496 568,five hundred thousand

five hundred thousand

Q5.
Round 654 023 to one significant figure.
Correct Answer: 700 000
Q6.
What value could the missing digit be in 3$$\square$$89 = 4000 (to 1 s.f.)?
3
4
Correct answer: 5
Correct answer: 6
Correct answer: 7