 # Rounding Off Numbers – Definition, Rules, Examples | How to Round Numbers to Nearest Ten, Hundred?

Rounding off numbers is an approximation that is used in our everyday life. It means it is a number that makes your calculations simpler by keeping the value closer to the next number. There are some rules for rounding off the numbers. Scroll down this page to know the rules for rounding off numbers. Rounding off numbers or significant figures is the basic concept that your child needs to learn at the primary level itself. Make your calculations easy by adjusting the number to the nearest values.

## Rounding Off Numbers – Definition

Rounding off is a process in which we make the number simple by keeping its value intact and closer to the next number. We can perform rounding off operations for decimal numbers, whole numbers, and so on. Rounding Off can be done at various places such as tens, hundreds, thousands, and so on. For Example 34.67 can be rounded to tens place is 34.7 i.e. hundreds place 7 is greater than 5 so we will increase the tens place by 1.

### Rules in Rounding Off Numbers

In order to make your problems easy, you need to follow some rules to round off the numbers. Go through the below section to know the rules for rounding numbers.

• If the digit to be dropped while rounding off is 5 or greater than 5, the following digit is increased by 1.
• If the digit to be dropped while rounding off is less than 5, the following digit is left unchanged.
• All the zeros that are between non-zero digits are significant.
• While rounding off a digit at a higher place value, we ignore the lower place value digits.
• All the non-zero digits in the number are significant.
• The zeros on the right of a non-zero digit in a whole number are significant.

Do Refer:

#### Rounding Off Whole Numbers

Follow the step-by-step process listed below to become familiar with the concept of Rounding Whole Numbers. They are as such

1. To get the accurate value, always choose the smaller value in the unit’s place.
2. The digit previous to this place should be compared with 5.
3. If it is less than 5, all the digits towards its left will be replaced by 0.
4. If it is greater than 5, all the digits towards its left will be replaced by 0.

#### Rounding Off Decimal Numbers

Know the simple process for rounding off decimal numbers and estimate the nearest values easily. They are as under

1. If the digits at the righthand side are less than 5, consider them as equal to zero.
2. If the digits at the righthand side are greater than or equal to 5, then add +1 to that digit.

### Types of Rounding Off Numbers

Rounding Numbers can be of different types such as rounding to nearest tens, hundreds, thousands, and so on. They are along the lines

1. Rounding Off Number Nearest to Ten:
First, identify the digit present in the tens place. And then identify the next smallest place in the number. If the number in the smallest place is less than 5, then round up the digit.
Example:
The round-off number 78 nearest to ten is 80.
Because 8 is greatest than 5 so we can add to the tens place and the unit’s place will be 0.

2. Rounding Off Number Nearest to Hundred:
First, identify the digit present in the hundreds place. And then identify the next smallest place in the number. If the number in the smallest place is less than 5, then round up the digit.
Example:
The round-off number 789 nearest to hundred is 800.

3. Estimation of Sum or Difference:
The first step in estimating a sum or a difference is to round the numbers, by changing them to the nearest power of ten, hundred, thousand, etc. Round the numbers first, then use mental math to estimate an answer.

#### Rounding Off Numbers Examples

Example 1.
We have the numbers 212 and 301. Write the roundoff number nearest to a hundred?
Solution:
212 is closer to 200 and 301 is closer to 300.
So, the number nearest to hundred is 200 and 300.
Example 2.
Round off to the nearest 10 in each of the following numbers:
a. 17
b. 38
c. 71
d. 68
Solution:
First, identify the digit present in the tens place. And then identify the next smallest place in the number. If the number in the smallest place is less than 5, then round up the digit.
a. 7 is greater than 5 so we should add 1 to the next digit.
The number closer to 17 is 20.
b. 8 is greater than 5 so we should add 1 to the next digit.
The number closer to 38 is 40.
c. 1 is less than 5 so the unit place remains 0.
The number closer to 71 is 70.
d. 8 is greater than 5 so we should add 1 to the next digit.
The number closer to 68 is 70.

Example 3.
Estimate the sum of 810 and 99 by using the mental math that can be rounded to the nearest hundred.
Solution:
810 can be written as 800
99 can be written as 100
800 + 100 = 900

Example 4.
Estimate the sum of 717 and 102?
Solution:
717 > 700
717 can be rounded off to 700
102 can be rounded off to 100
700 + 100 = 800

Example 5.
Estimate 4986 and 2894?
Solution:
4986 can be rounded off to 5000.
2894 can be rounded off to 3000.
5000 + 3000 = 8000

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