Seeing as Cian had just finished rounding up to 10 or down to 0, dressed as a snow leopard, Ioan and Finny decided they would incorporate animals into their rounding work too.
Resources
- Numicon
- Snow leopard
- Panda
- Macaw
- Whiteboards and pens
Steps for rounding to the nearest 10
- Look at the digit in the ‘Ones’ column:
- if it is less than 5 then round the number down by changing the ones digit to zero;
- if it is 5 or more then round the number up by adding one on to the tens digit and changing the ones digit to zero.
When you are rounding a number to the nearest 10, you are trying to find out which multiple of 10 your number is closest to. If a number is exactly halfway between two multiples of 10, you always round up.
Finny started by rounding 628 to the nearest ten. He identified that he needed to look at the digit in the ones column.
Finny’s digit was 8, so he changed the ones digit to zero and needed to round up the tens from 20 to 30.
Steps for rounding to the nearest 100
- Look at the digit in the ‘Tens’ column:
- if it is less than 5 then round the number down by changing the tens and ones digits to zero;
- if it is 5 or more then round the number up by adding one on to the hundreds digit and changing the tens and ones digits to zero.
When you are rounding a number to the nearest 100, you are trying to find out which multiple of 100 your number is closest to. If a number is exactly halfway between two multiples of 100, you always round up.
Ioan looked at rounding 628 to the nearest hundred. He circled the digit in the tens column.
Ioan’s digit was 2, so he changed the tens and ones digits to zero and needed to round down the hundreds down to 600.
Steps for rounding to the nearest 1,000
- Look at the digit in the ‘Hundreds’ column:
- if it is less than 5 then round the number down by changing the hundreds, tens and ones digits to zero;
- if it is 5 or more then round the number up by adding one on to the thousands digit and changing the hundreds, tens and ones digits to zero.
When you are rounding a number to the nearest 1,000, you are trying to find out which multiple of 1,000 your number is closest to. If a number is exactly halfway between two multiples of 1,000, you always round up.
Finny rounded 628 to the nearest thousand. He circled the digit in the hundreds column.
His digit was 6, so he changed the hundreds, tens and ones digits to zero and needed to round up the thousands to 1,000.
Being giant pandas and macaws
Ioan thought sitting down like a giant panda (and eating bamboo) would be a good way to represent rounding down.
Finny suggested that being a macaw, up in a tree, should show they were rounding up.
They started off rounding to the nearest 10:
5,678 rounds up to 5,680
9,918 rounds up to 9,920
1,209 rounds up to 1,210
Rounding to the nearest 100:
352 rounds up to 400
6,249 rounds down to 6,200
9,659 rounds up to 9,700
Rounding to the nearest 1,000:
2,311 rounds down to 2,000
3,560 rounds up to 4,000
7,058 rounds down to 7,000
Ioan and Finny then went on to record their answers.
My favourite snow leopard, giant panda and macaw, with all their hard work.
DfES National Curriculum (2013)
Numeracy Year 4 programme of study
Number – number and place value
- round any number to the nearest 10, 100 or 1,000.