Rounding Numbers: Concept, Rules, and Examples

Rounding numbers is a logical way of adjusting numbers that makes the calculation simpler and more practical for mathematics and daily use. We often follow the process of rounding numbers for bill payment, time estimations, or quick mental calculations to avoid handling large numbers or decimal values.

It’s one of the best methods to handle math problems involving large values, decimals, or fractions especially where very high precision in results is not required. 

Here, we will discuss rounding numbers, the steps and the rules, and provide plenty of rounding number examples to make the concept crystal clear for students.

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What are Rounding Numbers?

Rounding numbers is an approximation process to arrive at easier figures close to the original numbers that become handy to deal with. 

It is typically performed by adjusting the digits to get the value for the nearest ten, hundred, thousand, etc. 

The purpose is to reduce long numbers and multiple digits into shorter and simpler forms, making them easier to read, write, and work with.

For example:

• The number 638 rounded to the nearest ten is 640.

• The number 2.547 rounded to two decimal places is 2.55.

The rounded number is not exactly the same but close enough to serve the purpose for practical calculations when exact values are not necessary.

Why Do We Round Numbers?

The objective of rounding numbers is to make the numbers simpler to handle. Let’s find out the major benefits of rounding numbers:

• Simplification: Large numbers become simpler to understand. For example, rounding 3789 to 3800.

• Estimation: Rounding helps in quick calculations such as estimating costs, distances, or quantities.

• Communication: It’s easier to convey rounded figures instead of lengthy digits or decimals.

• Practicality: Rounded values are used in measurements where exact values are either unnecessary or not possible.

Read more: Brackets in Maths: Types, Rules & Examples

Round Up and Round Down Numbers

Rounding off numbers can be done in two ways. 

We can round up a number that increases its value, or we can round down to decrease the value, depending on the digit we are working with. The basic rules for round up and round down are as follows:

Round Down

It is the process of rounding to a lower value close to the number. If the next digit is less than 5, the previous digit remains the same, while all digits to the right of it become zero (for whole numbers) or disappear (for decimals).

Example:

42 rounded down to the nearest ten is 40.

3.25 rounded down to the nearest whole number is 3.

Round Up

It is the process of rounding to a higher value close to the number. If the next digit is less than 5, we increase the previous digit by 1 and make the digits on the right zero (for whole numbers) or remove them (for decimals).

Example:

236 rounded up to the nearest ten is 240.

1.48 rounded up to one decimal place is 1.5.

Read more: Numerator and Denominator - Definition and Difference

Rules for Rounding Numbers

Students must clearly understand which approximate value is closer to the original number when rounding it off. The standard rules for rounding numbers are given below:

• Identify the place value for which rounding is to be done. It may be the nearest ten, hundred, thousand, decimal place, etc., depending on the requirements.

• Look at the digit immediately to the right of that place value, which will decide how the number will be modified.

• If that digit is less than 5, keep the rounding digit the same and remove all the digits to the right (round down).

• If the digit is 5 or more, increase the rounding digit by 1 and remove all digits to the right (round up).

Example:

Round off 4368 to the nearest 10.

Solution:

• Here, we will consider the digit at the tens place, which needs to be rounded.

• The digit at the right of 6 is 8, which is greater than 5.

• So, we will replace 6 with 7 and make the digit 8 zero.

• The number we get is 4370.

Therefore, the rounded value of 4368 to the nearest ten is 4370.

Read more: Zero divided by a number

How to Round Off Decimal Numbers?

Rounding off decimals follows the same rules as whole numbers. But, in this case, we have to consider the digits after the decimal point. 

Students must have a clear idea on how to round a number with decimals to any decimal place, such as tenths, hundredths, or thousandths. Here are the steps for how to round off decimal numbers:

• Identify the decimal place up to which you want to express the value.

• Identify the digit at that place, which will be rounded.

• Look at the digit immediately after that digit.

• Apply the rounding rules on that digit (round up if 5 or more, round down if less than 5).

• Remove all digits after the rounded digit.

Example 1:

Round 5.173 to two decimal places.

• Look at the second decimal place. The digit is 7.

• The next digit is 3. (< 5), so, we will round down.

• So, digit 7 remains unchanged, while 3 becomes zero.

• The rounding number is 5.17.

Example 2:

Round 8.279 to one decimal place.

• Look at the first decimal place. The digit is 2.

• The next digit is 7 (> 5), which indicates rounding up.

• So, we place 3 in place of 2, and all digits after are removed.

• The rounding number is 8.3.

Rounding Decimal Numbers to Whole Numbers

Sometimes, your child may require to round a decimal number to the nearest whole number for calculation purposes. The method mentioned below helps them carry out the operation easily and quickly.

• Identify the digit immediately after the decimal.

• If it is < 5, round down by removing the digits after the decimal.

• If the digit is ≥ 5, increase the digit before decimal by 1 and remove the digits after the decimal.

Examples:

• 9.2 - nearest whole number = 9 (round down).

• 23.6 - nearest whole number = 24 (round up).

Rounding Number Examples

Let’s go through some rounding number examples to easily understand the concept of rounding off numbers.

Rounding to the Nearest 10 Example

Examples:

• 59 - nearest 10 = 60 (since 9 ≥ 5, round up).

• 132 - nearest 10 = 130 (since 2 < 5, round down).

Rounding to the Nearest 100 Example

Examples:

• 384 - nearest 100 = 400 (since the tens digit is 8 ≥ 5).

• 241 - nearest 100 = 200 (since the tens digit is 4 < 5).

Rounding to Nearest 1000 Example

Examples:

• 6243 - nearest 1000 = 6000 (since the hundreds digit is 2 < 5, round down).

• 8845 - nearest 1000 = 9000 (since the hundreds digit is 8 ≥ 5, round up).

Read more:  Ascending Order - Definition, Formula, Symbol, Examples

Solved Rounding Number Examples

1. Round 72 to the nearest ten.

Answer: 70

Reason: The ones digit = 2 (<5)

2. Round 268 to the nearest hundred.

Answer: 300

Reason: The tens digit = 6 (≥5)

3. Round 2965 to the nearest thousand.

Answer: 3000

Reasons: The hundreds digit is 9 (≥5),

4. Round 1.285 to one decimal place.

Answer: 1.3

Reason: The tens digit is 2, and the next digit is 8 (≥5).

5. Round 3.647 to two decimal places.

Answer: 3.65

Reason: Hundredths digit = 4, next digit = 7 (>5)

6. Round 43.815 to the nearest whole number.

Answer: 44

Reason: The Tenths digit = 8 (>5).

Also read: Before Number Concept: Definition and Examples

Important Points Regarding Rounding Numbers

Students must be careful of points while rounding numbers to avoid mistakes. Here are some important points to remember:

• Always check the digit immediately to the right of the place value you are rounding to.

• After rounding, all digits to the right must be replaced with zero for whole numbers.

• Students must remember that 5 and above means round up and below 5 means round down.

• When working with decimals, be careful about the required decimal places for rounding.

A thorough understanding of rounding numbers with the rules for rounding makes the concept much simpler and easier for your child. They can acquire skills to round up and round down digits that help them handle numbers more efficiently in exams, daily life, or professional work.

Make Mental Math Easy For Your Child with CuriousJr Mental Maths Classes

Every child learns differently. Some understand numbers quickly, while others take a little more time and support. That does not mean they are behind, it only means they learn in their own way. At CuriousJr Mental Maths Classes, learning is made simple, engaging, and supportive so that children feel comfortable with numbers.

Lessons are paced in a way that no child feels rushed. Fun activities, visual methods, and interactive teaching make maths easier to connect with and less overwhelming. With two teachers guiding every class, children receive attention when they need it most, and parents are kept involved with regular updates about progress.

Step by step, children begin to solve problems faster, enjoy working with numbers, and build a strong base for the future. Book a demo class today to know more about our classes.