Rounding refers to the process of converting a particular number to an easy number. The rounded number is not exact but an estimate of the given number.
Usually, we round numbers for:
Estimation: We use rounding to guess the most appropriate answer. Rounding is the process of estimation.
For example, Samantha wants to buy chocolates for $97. She can estimate the amount to the nearest tens and give $100. The shopkeeper will return Samantha $3.
Estimation helps us to calculate easily.
We can follow the given steps to round numbers to the nearest tens:
Step 1 We look at the number we want to round.
Step 2 As we are rounding the number to the nearest tens, we mark the digit in the tens column.
Step 3 Now we look at the ‘ones’ column (the digit to the right of the tens column).
Step 4 (i) If the digit in the one's column is 0, 1, 2, 3 or 4, we will round down the tens column to the nearest tens.
(ii) If the digit in the one's column is 5, 6, 7, 8 or 9, we will round up the tens column to the nearest tens.
Step 5 Write ones digit as 0 and remove all the digits after the one's column. The left out number is our desired answer.
Example 1: Round 524 to the nearest ten.
Step Number 
Observation 
Working Out 
Step 1 
524 

Step 2 
We get 2 in the tens column. 

Step 3 
We get 4 in the one's column (right of 2) 

Step 4 
We get 4 in Step 3. 
RoundDown 
Step 5 
520 
We keep 2 as it is and write ones digit as 0 and remove all the digits from the right of the one's column. 
Example 2: Round 117.32 to the nearest tens.
Step Number 
Observation 
Working Out 
Step 1 
117.32 

Step 2 
We get 2 in the tens column. 

Step 3 
We get 7 in the one's column (right of 1) 

Step 4 
We get 7 in Step 3. 
RoundUp 
Step 5 
120 
We add 1 to the 1 at tens place and write one's digit as 0 and remove all the digits from the right of the one's column. 
Example 3: Tom is 149 cm tall. Write his height in the nearest tens?
Step Number 
Observation 
Working Out 
Step 1 
149 

Step 2 
We get 4 in the tens column. 

Step 3 
We get 9 in the one's column (right of 4) 

Step 4 
We get 9 in Step 3. 
RoundUp 
Step 5 
150 
We add 1 to 4 at the tens place and write one's digit as 0 and remove all the digits from the right of the ones column 
Exception case:
Example 4: Round the number 199.278 to the nearest tens.
Step Number 
Observation 
Working Out 
Step 1 
199.278 

Step 2 
We get 9 in the tens column. 

Step 3 
We get 9 in the one's column (right of 9) 

Step 4 
We get 9 in Step 3. 
RoundUp 
Step 5 
200 
We add 1 to 9 and carry 1 to hundreds column and write one's digit as 0 and remove all the digits from the right of the one's column. 
Example 5: A park measures 249.9 meters in length. How long is the park to the nearest 10 meters?
Step Number 
Observation 
Working Out 
Step 1 
249.9 

Step 2 
We get 4 in the tens column. 

Step 3 
We get 9 in the one's column (right of 4) 

Step 4 
We get 9 in Step 3. 
RoundUp 
Step 5 
250 
We add 1 to 4 and write ones digit as 0 and remove all the digits from the right of the ones column. 
Fun Fact
