Rounding Rules Explained with Practice Problems
In order to round off to the nearest whole number, we will have to see the first digit after the decimal point. If this digit is less than 5 (1, 2, 3, 4) we are not required to do anything, however, if the digit is 5 or greater (5, 6, 7, 8, 9) we must round up. For example, 4.5 rounded to the nearest whole number are 5. Generally, we round a number to the number which is closest to the original number.
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Rounding off Whole Numbers
In some mathematical instances, you would not need an exact answer. In such cases, rounding the number to a particular place value is possible. For example, if a car travelled 783 miles, you might want to round the distance to 800 miles, which is easier to think about.
Rules For Rounding Whole Numbers
Following are the rules for rounding whole numbers:
Step1: To round a whole number, determine the digit with the place value to which you are rounding. You might also highlight the digit circling it so you can focus on it better.
Step2: Identify the possible numbers which you would get by rounding. These possible numbers are close to the number which you’re rounding to, but contains zeros (o’s) in the digits to the right.
Step3: If you are rounding 276 to the nearest ten, then 270 and 280 are the two possible numbers to round to, since 276 is between 270 and 280. Since 280 are nearest then 276 can be rounded to 280 instead of 270.
Rounding Decimals to the Nearest Whole Number
Rounding decimals to the nearest whole number or the 10th, 100th, 1000th is easy! Rounding decimals enables us to manage the numbers more easily with respect to operating them.
In order to round up to the nearest whole number, you have to look at the first digit after the decimal point.
For example: If we have to round the number 5.36 to the nearest whole, then
We look into the digit after the decimal point which is 3. Seeing that it is less than 5, the number is closer to 5 than to 6, and so the rounded whole number is 5.
Rounding Decimals to the Tenths, Hundredths, Thousandths…
Let’s quickly learn how to round each decimal to the nearest whole number. For the purpose of rounding a decimal number, we need to look at the number after the one we want to round to. If we want to round to the nearest tenth, we will require focusing on the digit in the hundredths place. If we want to round to the nearest hundredth, we would require focusing on the digit in the thousandths place. If this digit is less than 5 (1, 2, 3, 4) we are required to do nothing, but if it is 5 or greater (5, 6, 7, 8, 9), we should round up.
Example: Round the given decimal number to the nearest tenth: 9.376
Solution: As mentioned earlier, we will focus on the digit after the tenths place (in the hundredths place), that is 7. Since 7 is greater than 5 we have to round up in the tenths place. The rounded number is 9.4, which means that 9.377 are closer to 9.4 than to 9.3.
Example: Round the given number to the nearest hundredth: 0.3848
Solution: As mentioned earlier, we will focus on the digit after the hundredths place (in the thousandths place), which is 4. Because it is less than 5, we would not require changing the digit in the hundredths place. The rounded number is 0.38. This means that 0.3848 is closer to 0.38 than to 0.39
Solved Examples
Example: Identity what is 43.89 rounded to the nearest whole percent?
Solution: If we are referring to 43.89% then the two nearest whole percents will be: 43% or 44%
From 43.89% up to 44% all you would require is to add 0.11% or a one-hundredth (1/100) of a percent.
From 43.89% down to 43% you would require to subtract 0.89% or ninety-nine one-hundredths (99/100) of a percent.
Thus, 99/100 is 99 times further than 1/100
Hence, 44% is the rounded nearest whole percent.
Usually, the rule is
50/100 round up and 49/100 round down
or:
5/10 round up and 4/10 round down
or:
500/1000 round up and 499/1000 round down
Fun Facts
Round to the nearest whole number comes in handy to see if a calculation is reasonable.
When a number is halfway between the two possible numbers, we must round up to the greater number.
FAQs on How to Round a Whole Number
1. What does it mean to round a number to the nearest whole number?
Rounding to the nearest whole number means simplifying a decimal number to the closest integer (a number without any decimal parts). It's a way of estimating to make numbers easier to work with. For example, if you have 3.9, the nearest whole number is 4.
2. What is the main rule for rounding a number to the nearest whole number?
The main rule is to look at the digit in the tenths place (the first digit after the decimal point).
- If this digit is 5 or more (5, 6, 7, 8, or 9), you round the whole number part up by one.
- If this digit is 4 or less (4, 3, 2, 1, or 0), you keep the whole number part as it is.
3. How would you round 57.8 to the nearest whole number?
To round 57.8, we first identify the digit in the tenths place, which is 8. Since 8 is '5 or more', we round up the whole number part. The '7' in 57 becomes '8'. Therefore, 57.8 rounded to the nearest whole number is 58.
4. What is 182.3 rounded to the nearest whole number?
To round 182.3, we look at the digit in the tenths place, which is 3. Since 3 is '4 or less', we keep the whole number part the same and drop the decimal part. Therefore, 182.3 rounded to the nearest whole number is 182.
5. What happens if the digit in the tenths place is exactly 5 when rounding?
This is a great question that often confuses students. The standard rule, as per the CBSE/NCERT curriculum, is that when the digit in the tenths place is exactly 5, you always round up to the next whole number. For instance, 23.5 would be rounded up to 24, and 149.5 would be rounded up to 150.
6. Why is rounding numbers a useful skill in daily life? Provide examples.
Rounding is extremely useful because it helps us make quick estimations without needing a calculator. It simplifies complex numbers for practical purposes. Key examples include:
- Shopping: If items cost ₹48, ₹99, and ₹152, you can round them to ₹50, ₹100, and ₹150 to quickly estimate the total bill will be around ₹300.
- Time Management: Saying you'll arrive in "about 30 minutes" is a form of rounding that is more practical than saying "28 minutes."
- Cooking: If a recipe needs 295g of flour, you can round it to 300g for easier measurement.
7. What is the key difference between rounding to the nearest whole number and rounding to the nearest ten?
The key difference is the place value you focus on to make your decision.
- When rounding to the nearest whole number (e.g., from 47.2), you look at the tenths place (the '2').
- When rounding to the nearest ten (e.g., from the whole number 47), you look at the ones place (the '7').
8. When rounding a large number like 4,872 to the nearest hundred, why do we look at the tens place?
We look at the tens place because the rule of rounding is universal: to round to a specific place value, you must always examine the digit immediately to its right. For rounding to the nearest hundred, the place value to the right is the tens place. The digit in the tens place (in this case, '7') tells you whether the hundreds value is closer to 800 or 900. Since 7 is '5 or more', we round the '8' in the hundreds place up to '9', making the result 4,900.
