Rounding
Maths: Year 5 & 6 National Curriculum, topic 5.1.3
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.
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.
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.
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.
Test yourself on Rounding
What is 495 rounded to the nearest 10?
What is 52,425 rounded to the nearest 10?
What is 1,456,156 rounded to the nearest 10?
What is 0.63 rounded to 1 decimal place?
What is 0.47 rounded to 1 decimal place?