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Rounding Numbers

rounding numbersWhy is it important to learn to round numbers? This is a practical skill that your kids will take with them into their everyday lives, because rounding numbers help us calculate sums easier in our heads.


For example, you and your friends are buying pizza and you want to make sure you have enough money to buy four large pizzas with various toppings. Rounding the cost of each pizza to the nearest dollar and adding the amounts is a quick and easy way to make sure you have enough money to pay for them.

 


So, we round numbers because:


It makes it easier to describe and understand numbers.
It makes it easier to estimate answers to numeracy questions.


If you think about it, we actually round all the time:

rounding numbers

 

 

 

 

 

 

 

How do you round numbers?


There’s one rule you need to follow when rounding:


0, 1, 2, 3 and 4 always go down.
5, 6, 7, 8 and 9 always go up.


Next, you need to pay attention to what digit that needs to be rounded.


For example: round 63 to the nearest 10.

We keep the 6, as it’s in the 10s position.
The next digit is 3, which is less than 5, so it goes down.

The answer is 60.


However, if the single digit is more than 5, you need to go up.


For example: round 67 to the nearest 10.

We keep the 6.
The next digit is 7, which is more than 5, so it goes up, effectively adding 1 to the 6.1 + 6 = 7.

The answer is 70.


Pay attention to what nearest number you are being asked to round to.


In the above examples, we rounded to the nearest 10. But what if you are asked to round to the nearest hundred?


To round numbers to the nearest hundred, make the numbers that end in 1 through 49 into the next lower number that ends in 00.

For example 524 rounded to the nearest hundred is 500.


Numbers that have the last two digits of 50 or more should be rounded up to the next even hundred.
For example, 678 rounded to the nearest hundred is 700.


For your kids to practice rounding numbers we offer worksheets for grade 2, grade 3, grade 4 and grade 5 in our math worksheet center.