Basics, Worksheet, and More: A Guide to Rounding Off – Updated

The mathematical notion of rounding off has many applications across many disciplines. Rounding off can make computations easier and data more manageable when working with huge numbers or decimal values. 

This blog will offer a thorough tutorial for understanding the skill of rounding off, whether you are a student, professional, or just interested in Mathematics. This article will cover the following:

1. What is Rounding Off?
2. Download the Free Sample Worksheet
3. Rounding Rules for Whole Numbers
4. Rounding Rules for Decimal Numbers
5. Example of How to Round Off

What is Rounding Off? 

Rounding off is a standard mathematical operation that involves approximating a number to a given level of accuracy. When you round a number, you adjust it to the nearest value that is easier to work with or more meaningful for the given context.

For example, if you have a number with many decimal places, it may be more convenient to round it off to a certain number of decimal places. Similarly, if you have a large number that is difficult to work with, you should round it off to a smaller value.

There are different rules for rounding off numbers, depending on the desired level of accuracy and the convention being used. The most common way to round a number is to look at the digit immediately to the right of the desired accuracy level and round up if it is greater than or equal to five or round down if it is less than five. 

Rounding Rules for Whole Numbers

Rounding off whole numbers is a fundamental mathematical skill that involves adjusting a number to the nearest multiple of a given value. While the most common values are 10, 100, and 1000, other values can also be used. 

Follow these basic rounding rules: round to the nearest ten by looking at the units digit, round to the nearest hundred by looking at the last two digits, and round to the nearest thousand by looking at the last three digits. With these rules, you can quickly and easily round off whole numbers in various contexts.

Example: 

1. Round 752 to the nearest hundred. The last two digits are 52, greater than 50, so we round up to 800.
2. Round 7,361 to the nearest thousand. The last three digits are 361, less than 500, so we round down to 7000.

Rounding Rules for Decimal Numbers

Rounding off decimal numbers involves adjusting a number to a certain number of decimal places or significant figures. The rounding rules for decimal numbers are based on the digit in the place immediately following the desired level of accuracy. Here are the basic rounding rules for decimal numbers:

Round to a certain number of decimal places: Look at the digit in the place immediately to the right of the desired decimal place. If it is 5 or greater, round up the last digit to the desired decimal place. If it is less than 5, round down the last digit to the desired decimal place.

Example: Round 3.789 to two decimal places. The digit in the third decimal place is 9, 5 or greater, so we round up the last digit to get 3.79.

Round to a certain number of significant figures: Count the number of significant figures. Look at the digit in the place immediately following the desired number of significant figures. Suppose it is 5 or greater; round up the last significant figure. If it is less than 5, leave the last significant figure as is.

Example: Round 52.376 to three significant figures. The first three digits are significant, so we look at the digit in the fourth place, which is 6. Since 6 is 5 or greater, we round up the last significant figure to get 52.4.

It’s important to note that when rounding off decimal numbers, you should keep in mind the context in which the number is being used and choose the appropriate level of accuracy. 

Rounding off can introduce some degree of error into calculations, so it’s important to use it appropriately and with caution.

Free Sample Worksheet

Q1. Round off 6093 to the nearest thousands.

1. 6000
2. 6100
3. 6500
4. 7000

Q2. Find the result of the following operation using Rounding Off to the nearest hundreds:

5977- 2343.

1. 3500
2. 3700
3. 3800
4. 3600

Q3. A number has 9, 0, and 9 as its digits. Rounding off the number to the nearest 100 gives 900.

Find the number.

1. 990
2. 099
3. 909
4. None of the above

Q4. Calculate using mental math skills: 88 X 5

1. 445
2. 420
3. 440
4. 480

Q5. What is 46 X 50 (calculate mentally)

1. 2200
2. 2250
3. 2350
4. 2300

Q6. What is 12 X 500 (calculate mentally)

1. 600
2. 6000
3. 6500
4. 1200

Q7. Round off the number 9,876 to the nearest ten thousand place.

1. 10,000
2. 9,8000
3. 9,9000
4. 9,7000

Q8. How much is 16 x 50

1. 800
2. 8000
3. 400
4. 4000

Q9. Calculate mentally: 34 X 500

1. 17,500
2. 16,000
3. 17,000
4. 16,500

 Q10. Calculate 322 X 5

1. 1620
2. 161
3. 151
4. 1610

Download the full worksheet with answers now!

Example of How to Round Off

Here’s an example of how to round off a number:

Let’s say you have the number 3.5678, and you want to round it off to two decimal places.

Step 1: Look at the third decimal place, which is 7.

Step 2: Since 7 is greater than or equal to 5, you need to round up the second decimal place.

Step 3: Add 1 to the second decimal place, which is 6. This gives you 7.

Step 4: Drop all decimal places to the right of the second decimal place. This gives you 3.57.

So the rounded-off value of 3.5678 to two decimal places is 3.57.

Similarly, if you wanted to round off 567.89 to the nearest ten, you would follow these steps:

Step 1: Look at the unit digit, which is 9.

Step 2: Since 9 is greater than or equal to 5, you need to round up to the nearest ten.

Step 3: Add 1 to the tens place, which is 8. This gives you 9.

Step 4: Drop all digits to the right of the tens place. This gives you 570.

So the rounded-off value of 567.89 to the nearest ten is 570.

These are just a few examples of how to round off a number. The method and level of accuracy will depend on the specific context and requirements of the calculation.

Example of How to Round Off to Nearest Hundred

Suppose we have the decimal number 58.936, and we want to round it off to the nearest hundred. To do this, we look at the digit in the hundreds place, which is 5. The digit immediately to the right of it is 8, which is greater than or equal to 5. Therefore, we need to round up the digit in the hundreds place by adding 1.

When we round up the digit in the hundreds place, the digits in the tens and one’s place become irrelevant. So, the number 58.936 becomes 59.000 after rounding up to the nearest hundred.

Therefore, when we round off 58.936 to the nearest hundred, we get 59.000.

Example of How to Round Off to Nearest Ten

Suppose we have the whole number 78, and we want to round it off to the nearest ten. To do this, we look at the unit digit 8. Since 8 is greater than or equal to 5, we must round up the tens digit by adding 1.

When we round up the tens digit, the units digit becomes 0. So, the number 78 becomes 80 after rounding up to the nearest ten.

Therefore, when we round off 78 to the nearest ten, we get 80.

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