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L.C: To estimate answers

Today we are going to use estimation to work out answers.

Discuss with the person next to you.

How did Laura work out her answer?

What method did Fatima use?

Which do you think is the best method and why?



When estimating numbers we use our rounding knowledge. This makes the numbers easier to add or subtract.


459 rounded to the nearest  100 = 500

1342 rounded to the nearest 100 = 1300

951 rounded to the nearest 100 = 1000

When rounding to the nearest 100 you must look at the tens digit if its is 5 or more you round the number up to the next 100

For example: 459 is rounded up to 500 because the tens digit is 5. 

If the tens digit is 4 or less you round the number down to the previous 100 

For example: 342  will be rounded to 300 because the tens digit is 4. 


Once the numbers have been rounded to the nearest 100 we can easily add the numbers together. 

500 + 1300 + 1000 = 2800

Task 1

Look at the information below and fill in the missing numbers. You need to round the numbers to the nearest 1000, 100 and 10. 

Part of the answer has been done for you.