Page 102 - Math Skill - 5

7 7 Estimation
Estimation

Learning Outcomes
� Rounding off Numbers � Rounding off Decimals � Rounding off Decimal Quotients

Boot-Up

Answer the following using the number cards. You can’t repeat the number cards.

1. Write the largest 6-digit number using these number cards. ____________________________

Round off to nearest thousand. ____________________________
2. Write the smallest 5-digit number using these number cards. ____________________________
Round off this number to nearest hundred. ____________________________
3. What is the sum of largest five-digit number and the smallest ____________________________
four-digit using the given number cards.

And round off the sum to nearest tens. ____________________________

Estimation or rounding off means making a ‘fair guess’ about numbers. It is also called
approximation.

We use estimation in our daily life very often.

For example, a statement like “a TV costs around ` 20,000” is an estimation.
We have learned about estimation in Class IV. Let’s revise the concept of estimating numbers
once again.

Rounding off Numbers
To round off numbers, we follow these steps:

Step 1: If the digit on the right of the rounding place is greater than or equal to 5, add 1 to the
digit at the rounding place, otherwise do not change the digit at the rounding place.

Step 2: Replace all digits to the right of the rounding place by zeroes.

We can round off a given number to the nearest tens, hundreds, thousands, lakhs or crores.
Let’s learn through examples.