Year 6

We can round numbers to any degree of accuracy

Year 6 Unit 8b

What we are learning:

• Once we are confident with numbers we can round them to any degree of accuracy. This is useful in lots of mental calculations to get ‘approximate’ answers, or estimations.
• Remember the rule for rounding – if the number we are rounding is half way or more towards the next rounded number we round UP.
• We can round very large numbers in this way
  If we start with the number 144,573
  We can round 144,573 to the nearest 10 = 144,570
  We can round 144,573 to the nearest 100 = 144,600
  We can round 144,573 to the nearest 1000 = 145,000
  We can round 144,573 to the nearest 10,000 = 140,000
  We can round 145,573 to the nearest 100,000 = 100,000

Rounding decimal places

• Decimal places can be rounded to the nearest whole number.
  0.34 rounds to 0 because it is less than half way to 1.0
  0.56 rounds to 1.0 because it is more than half way to 1.0
  22.09 rounds to 22.0 but 22.90 rounds to 23.0
  30.49 rounds to 30.0 but 30.50 rounds to 31.0
• We can round large numbers to different degrees of accuracy
  If we start with the number 3,489
  We can round 3,489 to the nearest 10 = 3,490
  We can round 3,489 to the nearest 100 = 3,500
  We can round 3,489 to the nearest 1,000 = 3,000
  Sometimes we have to round the number up, and sometimes down depending on the number and the target for rounding.
• We can also round numbers with two decimal places to one decimal place
  We can round 13.52 to 13.5
  We can round 24.08 to 24.1
• We can round numbers with two decimal places to the nearest whole number
  We can round 13.52 to 14.0
  We can round 24.08 to 24.0

ACTIVITY 1: ROUNDING TO TWO DECIMAL PLACES

Activities you can do at home:

Try rounding the numbers on the activity sheet.
When you are out and about try looking at numbers and rounding them in a way that makes sense:
If you look at a TV that costs £449 ask your child to round the amount to the nearest £10
If you look at a car that costs £18,799 ask your child to round it to the nearest £100 or the nearest £1000

Good questions to ask:

What is that number rounded to the nearest …….?
Why is it helpful to round numbers sometimes?
What happens if we try to round a number too far, e.g. round 501 to the nearest 1000?
Why do you think so many shop prices end in 99p, e.g. £4.99 instead of £5.00?
These are good for starting discussion about how we use everyday numbers

If your child:

Gets confused when rounding large numbers
Start by rounding to the nearest 1 or 10 so that you only have to look at the units and tens column of the number you are rounding. Build up confidence before extending to rounding to 1000 and more.
Talk about the value of the numbers you are rounding – this will help and show you where the misunderstanding is happening.