5.1.3

Rounding

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Rounding

Rounding is the process of making a number more simple. Rounding is when you use a place value column to "round off" a number. We can use rounding to help us estimate!

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864,721

  • We need to look at the place value in order to help us round.
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864,721

  • If we were to round to the nearest 10, we need to look at the column to the right of the 'tens' column to work out how you will be rounding.
    • The column to the right of the 'tens' column is the 'ones' column.
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How many 'ones' in 864,721?

  • We have 2 'tens' and 1 'ones'.
    • If the digit in the 'ones' is 5 or above then we round the 'tens' up.
    • If the digit in the 'ones' is 4 or below then we round the 'tens' down.
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Rounding the number

  • There is 1 in the 'ones' column.
  • 1 is below 4 so you need to round down.
    • We must round our 'tens' column down to 864,720.
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Remember!

  • If we rounded up, the digit in the 'tens' column would change.
  • But we rounded down and this means that the digit in the 'tens' column stays the same.
    • Our 2 'tens' did NOT go down to 1 'ten'.
    • Our 2 'tens' rounded down and stayed at 2 'tens'.

Rounding Decimals

You can round numbers to a certain number of decimal places.

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3.36

  • We can round 3.36 to either 1 decimal place or to the nearest whole number.
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Rounding to 1 decimal place

  • To round to 1 decimal place (1dp), we need to look at our hundredths column.
    • We need to look at the hundredths column because it is the column to the right of our 1st decimal place.
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5 or above

  • There are 6 hundredths in 0.36.
    • We know that we need to round the digit up if it is 5 or above.
    • So, 3.36 rounded to 1 decimal place is 3.4.

Jump to other topics

1Year 5 - Number

2Year 5 - Measurement

3Year 5 - Geometry

4Year 5 - Statistics

5Year 6 - Number

6Year 6 - Ratio & Proportion

7Year 6 - Algebra

8Year 6 - Measurement

9Year 6 - Statistics

9.1Displaying Data

9.2Averages

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