Rounding – Definition with Examples

What Do You Mean by Rounding Off a Number?

Rounding off is nothing but estimation. Estimating the actual number to its nearby number is called rounding off. 

Example of Rounding Off from Everyday Life!

When someone asks you the price of your book, you say 100 even if it is 98. This is giving an estimation after rounding off a number. This is how we apply the concept of rounding off in our everyday life. 

How to Round Off Different Numbers?

Different numbers use different ‘rounding off’ rules. Let’s discuss them one by one.

Whole Numbers

Whole numbers are rounded off at different place values. 

Nearest Ten

Check the unit place digit:

  • If the unit place digit is less than 5 then keep the tens place digit the same and put 0 at the unit place. 
  • If the unit place is 5 or more than 5 then change the tens digit into its successor and put 0 at the unit place. 

Example: 

If we round off 15,493 to the nearest tens place then the answer will be 15,490. 

As the unit place is less than 5, the tens place digit will not change. 

Similarly, if we round off 12,359 to its nearest tens place then the answer will be 12,360.

As the unit place is more than 5, the tens place digit will change its successor. 

Nearest Hundred

Check the tens place digit:

  • If the tens place is less than 5 then keep the hundred place digit the same and put 0 at the tens and unit place. 
  • If the tens place is 5 or more than 5 then change the hundred digit into its successor and put 0 at the tens and unit place.

Example:

If we round off 15,443 to the nearest hundred places then the answer will be 15,400. As the tens place is less than 5, the hundred place digit will not change. 

Similarly, if we round off 12,359 to its nearest hundred places then the answer will be 12,400. 

As the tens place is 5, the hundred place digit will change to its successor. 

Nearest Thousand

Check the hundred place digit:

  • If the hundred place digit is less than 5 then keep the thousand place digit the same and put 0 at the hundred, tens, and unit place. 
  • If the hundred place digit is 5 or more than 5 then change the thousand place digit into its successor and put 0 at the hundred, tens, and unit place. 

Example:

If we round off 15,443 to the nearest thousand place digit then the answer will be 15,000. As the hundred place digit is less than 5, the thousand place digit will not change. 

Similarly, if we round off 12,659 to its nearest thousand place digit then the answer will be 13,000. 

As the hundred place digit is more than 5, the thousand place digit will change to its successor. 

Decimal Number

The concept is quite similar to the whole number with some minor but noteworthy changes. If the digit right to the place value you are rounding to is less than 5, round down. However, if it’s 5 or more than 5, round up.

Nearest Whole

5.9165 rounded to the nearest whole is 6.

As 5 is followed by 9 and 9 is greater than 5. So, round up.

Nearest Tenth

5.9165 rounded to the nearest tenth is 5.9

As 9 is followed by 1 and 1 is smaller than 5. So, round down.

Nearest Hundredth

5.9165 rounded to the nearest hundredth is 5.92.

As 1 is followed by 6 and 6 is greater than 5. So, round up.

Nearest thousandth

5.9165 rounded to the nearest thousandth is 5.917.

As 6 is followed by 5. So, round up.

Solved Examples 

Example 1.
Round off the following numbers to the nearest ten:

  1. 5499
  2. 3,453
  3. 4,405

Solution 1. 

  1. 5,499 rounded to the nearest ten is 5,500.

The unit place digit is more than 5 so add one to the tens place digit. 

  1.  3,453 rounded to the nearest ten is 3,450.

The unit place digit is less than 5 so the tens place digit will remain the same. 

  1. 4,405 rounded to the nearest ten is 4,410.

The unit place digit is 5 so add one to the tens place digit. 

Example 2.
Round off the following numbers to the nearest hundredth.

  1. 2.656
  2. 2.305
  3. 3.234

Solution 2. 

  1. 2.656 rounded to the nearest hundredth is 2.66.

The digit next to the hundredth place digit is more than 5 so add 1 to the hundredth place digit. 

  1. 2.305 rounded to the nearest hundredth is 2.31.

The digit next to the hundredth place digit is 5 so add 1 to the hundredth place digit. 

  1. 3.234 rounded to the nearest hundredth is 3.23.

The digit next to the hundredth place digit is less than 5 so the hundredth place digit will remain the same. 

Example 3.
Round off the following numbers to the nearest thousand. 

  1. 44,590
  2. 66,235

Solution 3.

  1. 44,590 rounded to the nearest thousand is 45,000.

The hundred place digit is 5 so add 1 to the thousand place digit. 

  1. 66,235 rounded to the nearest thousand is 66,000.

The hundred place digit is less than 5 so keep the thousand place digit the same as before.

Practice Problems

Rounding off

Attend this Quiz & Test your knowledge.

1A number rounded to the nearest 10 is 500. What could be the possible number?

400
259
495
555
CorrectIncorrect
Correct answer is: 495
495 will be rounded off to 500.

2Simplify the following after rounding off each number to the nearest hundred
45,789 + 23,848 + 66,321 – 34,213

202,700
101,700
234,000
434,000
CorrectIncorrect
Correct answer is: 101,700
45,800 + 23,800 + 66,300 – 34,200 = 101,700

3Match the numbers with their round off to the nearest tens.

Rounding – Definition with Examples
1-a, 2-b, 3-c
1-c, 2-b, 3-a
1-b, 2-c, 3-a
1-b, 2-a, 3-c
CorrectIncorrect
Correct answer is: 1-b, 2-c, 3-a
4,509 will round to 4,510. 98,683 will round to 98,680. 21,498 will round to 21,500.

Frequently Asked Questions

Yes. Heights and lengths can be rounded off.

If we round off 9,999 to the nearest hundred, we will get 10,000.

No. Round-off figures are not exact but are in proximity to the exact figure.