How to round decimals ? | Rounding Numbers Guide

a tutor help a student with decimal values. Teaching them a great rounding strategy. The student uses the common rounding methods.

How do you know when to round up decimals?

A table to help with rounded values. It shows units, tenths, hundredths, thousandths and ten thousandths.

When dealing with decimal numbers, rounding is an important concept that everyone should master. Rounding is useful in different situations: rounding to pay bills or in an academic setting to find out the estimate of the average score of students in a class.

The common rounding strategy consists of rounding a decimal number to a certain number of decimal places, to save time and help us express really long numbers in shorter terms.

We can round decimals to the nearest wholes, tenths or hundredths, when having exact values isn’t important. A rounded value has almost the same value as the original number but it is a bit less exact.

 

What are the rules for rounding off decimals?

There are certain rounding rules to follow when rounding a decimal number. Put simply, if the last digit is less than 5, round the previous digit down. However, if it’s 5 or more than you should round the previous digit up.

So, if the number you are about to round is followed by 5, 6, 7, 8, 9 round the number up. And if it is followed by 0, 1, 2, 3, 4 round the number down.

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Rounding Example

Consider the number 5.9163

5.9163 rounded to the nearest tenth digit is 5.9

  • Because 9 is followed by 1 and 1 is less than 5.

5.9163 rounded to the nearest hundredth digit is 5.92

  • Because 1 is followed by 6 and 6 is greater than 5.

5.9163 rounded to the nearest thousandth digit is 5.916

  • Because 6 is followed by 3 and 3 is less than 5.

 

How to round to two decimal places?

Rounding decimals to two decimal places is the same as rounding to the nearest hundredth. To round a number to the nearest hundredth, look at the digit at the right of the hundredth place and apply the same rule:

If the digit in the thousandth place is 0, 1, 2, 3, 4, you will round down to the nearest hundredth or just remove all digits found at the right.

But, if the digit in the thousandth place is 5, 6, 7, 8, 9, you have to round up to the nearest hundredth, and then remove all the digits on the right.

 

A table to help with rounded values. It shows units, tenths, hundredths, thousandths and ten thousandths. It shows where the hundredths digit is and what the student needs to calculate.

Rounding Example 1

Consider the number 8.254

8.254 rounded to two decimal places is 8.25

  • Because 5 is followed by 4 and 4 is less than 5.

 

Rounding Example 2

Consider the number 4.738

4.738 rounded to the nearest hundredth digit (two decimal places) is 4.74

  • Because 3 is followed by 8 and 8 is greater than 5.

 

How to round to 4 decimal places?

Rounding decimals to four decimal places refers to rounding to the nearest ten thousandth. To round a decimal number to the nearest ten thousandth, look at the digit one place to the right of the fourth place (look at the 5th place).

If the digit there is 5 or greater, you round up to the nearest ten thousand; and if the digit in the 5th place is less than 5, you round down to the nearest ten thousand or you just remove all the digits after the fourth place.

 

A chartboard to help with rounded values. It shows the units, the tenths, the hundreths, the thousandths and the ten thousandths. It shows where is the ten thousandths digit and what the student has to calculate.

Example 1

For this example, we will consider the number π , which equals to 3.1415926…

3.1415926 rounded to four decimal places (nearest ten thousandth) is 3.1416

  • Since the number in the 5th place is 9, which is greater than 5.

 

Example 2

For this, we will take the number 20.35784

20.35784 rounded to the nearest ten thousandth is 20.3578

  • As the number after the fourth place is 4, which is less than 5.

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How to round a number to the nearest integer (whole number)?

To round a number to the nearest integer—which is a whole number in this case—you need to look at the tenths digit. If the number you are about to round is followed by 5, 6, 7, 8, 9 round it up. And if it is followed by 0, 1, 2, 3, 4 round the number down.

 

Example 1

For this example, we will consider the number 5.7.

5.7 rounds up to 6.

  • Because 5 is followed by 7, which is greater than 5.

 

Example 2

For this example, we will consider the number 2.31.
2.31 rounds up to 3.

  • Because 2 is followed by 3, which is less than 5.

 

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Having trouble with rounding precision? Need help to recognize the hundredths digit? Do you need help assimilating the most common rounding methods? Does your child need help getting the correct answer to a common rounding task?

Do they need additional exercises to apply their decimal rounding learning? Our math tutors can help, whatever the subject or level. Simply click on the button below to make your request.

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Frequently asked questions

What is the rhyme for rounding?

It goes like this: “Four or less, let it rest; Five or more, let it soar.”

 

What are the 3 steps for rounding?

  1. Choose the place value of the number to be rounded;
  2. Look at the number on the right;
  3. If it’s ≤4, round down; if it’s ≥5, round up.

 

Do you round 0.49 up or down?

If you want to round 0.49 to the nearest tenth, since 9 is greater than 5, the answer is 0.5. If you want to round 0.49 to units, since 4 is less than 5, the answer will be 0.

 

How do you round 14.9962 to 2 decimal places?

To round 14.9962 to two decimal places, look at the number in place of the hundredths, which is 9, and the number to its right, which is 6. Since 6 is greater than five, round up to the next higher number, which gives 15.00.

 

What is 34.9961 rounded to the nearest ten?

To round 34.9961 to one decimal place, look at the tenth digit, which is 9, and the digit to its right, which is 9. Since 9 is greater than five, round up to the next digit, which is 35.

 

In which grade do you learn to round decimals?

Around 4th and 5th grade.

 

Do calculators have a rounding mode?

Most calculators don’t have a rounding mode, so it’s useful to know the normal rounding rules.


 

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