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Rounding

Rounding to 10

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.

The golden rule with rounding is that if a number is exactly halfway between two multiples of 10, you always round up.

 

How to round a number to the nearest 10

Look at the ones digit.

  • 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.

Examples

  • 37 rounds up to 40 because the ones digit is 7.
  • 63 rounds down to 60 because the ones digit is 3.
  • 145 rounds up to 150 because the ones digit is a 5.

 

Rounding to 100

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.

How to round a number to the nearest 100

Look at the tens digit.

  • if it is less than 5 then round the number down by changing the tens digit and ones digit 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 digit to zero.

Examples

  • 287 rounds up to 300 because the tens digit is 8.
  • 1629 rounds down to 1600 because the tens digit is 2.
  • 950 rounds up to 1000 because the tens digit is a 5.

 

Rounding to 1000

When you are rounding a number to the nearest 1000, you are trying to find out which multiple of 1000 your number is closest to.

How to round a number to the nearest 1000

Look at the hundreds digit.

  • 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.

Examples

  • 4687 rounds up to 5000 because the hundreds digit is 6.
  • 8296 rounds down to 8000 because the hundreds digit is 2.
  • 11583 rounds up to 12000 because the hundreds digit is a 5.

 

Rounding to 10, 100 & 1000

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