How to Round a Number

Definition - Rounding is to determine which number is closer to the original
Purpose - to make the numbers easier to work with

Rounding a number
1. Locate the place value position to be rounded
2. Underline the number or mark it in some way
3. Look at the digit to the right of the number you underlined
4. If the number is 4 or smaller, do not change the underlined number. However, change all numbers to the right of the underlined number to zeros.

If the number is 5 or higher, add 1 to the underlined number. Also, change all numbers to the right of the underlined number to zeros.
Example 1: Round 526 to the nearest hundred
The task is to determine whether 526 is closer to 500 or 600. For a moment, visualize a number line. Place a dot on 500 and 600. Next, put your finger on 526. Is it closer to 500 or 600? 500

Let's follow the above steps to prove our answer.

Step 1 & 2 - The 5 is in the hundreds place. 526
Step 3 - the 2 is the digit to the right
Step 4 since 2 is smaller than 4, the 5 is unchanged and the numbers to the right of 5 are changed to zeros

Answer: 526 is rounded to 500.


Example 2: Round 684 to the nearest hundred
The task is to determine whether 684 is closer to 600 or 700

Step 1 & 2 - The 6 is in the hundreds place. 684
Step 3 - The 8 is the digit to the right
Step 4 - Since 8 is larger than 5, add one to the 6, and change the numbers to the right of 6 to zeros

Answer: 684 is rounded to 700.


Example 3: Round 2,684 to the nearest ten
The task is to determine whether 2,684 is closer to 2,680 or 2,690

Step 1 & 2 - The 8 is in the tens place. 2,684
Step 3 - the 4 is the digit to the right
Step 4 since 4 is smaller than 5, the 8 is unchanged and the numbers to the right of 8 are changed to zeros. Alert! The numbers to the left of the underlined number, 8, do not change!

Answer: 2,684 is rounded to 2,680.


Example 4: Round 65,427 to the nearest ten thousand
The task is to determine whether 65,427 is closer to 60,000 or 70,000.

Step 1 & 2 - The 6 is in the ten thousands place. 65,247
Step 3 - The 5 is the digit to the right
Step 4 - Since 5 is equal to 5 or more, add one to the 6, and change all numbers to the right of 6 to zeros

Answer: 65,427 is rounded to 70,000.


Example 5: Round 43,972 to the nearest hundred
The task is to determine whether 43,972 is closer to 43,900 or 44,000

Step 1 & 2 - The 9 is in the hundreds place. 43,972
Step 3 - The 7 is the digit to the right
Step 4 - Since 7 is larger than 5, add one to the 9, and change the numbers to the right of 9 to zeros. (…for some, adding 1 to 9 poses a dilemma; simply change 9 to 10 by replacing the 9 with 0 and add the 1 to the 3 which is in the thousands place.)

Answer: 43,972 is rounded to 44,000.



If you need a review of place value, refer to the article, Place Value.