Skill Building
In this post, we are going to learn more about estimation and rounding.
Rounding
Let us look at this poem.
Example 1:
Round off 4 785 to the nearest 100.
Digit 7 is in the hundreds place.
Digit 8 is to its right.
Since 8 is more than 5, you need to add 1 to 7 to make it 8.
You need to convert digit 8 and 5 into 0 since you are rounding the numbers to the nearest 100.
Your answer should be 4 800.
Example 2:
Round off 24 385 to the nearest 1000.
Digit 4 is in the thousands place.
Digit 7 is to its right.
Since 3 is less than 5, you just ignore.
Digit 4 remains the same and convert digit 3, 8, and 5 to 0 since you are rounding the numbers to the nearest 1000.
Your answer should be 24 000.
Estimation
Estimation is used to predict the answer to a calculation. However, you need to round numbers to make your calculations easier and quicker to approximate your answer.
Example 1:
How do we estimate 11 x 13?
Round off 11 to the nearest 10.
10 x 13 = 130.
Example 2:
Estimate 115 x 79.
Round off 79 to the nearest 10, that is, 80 and 115 to the nearest 100, that is, 100
100 x 80 = 800
Rounding
Let us look at this poem.
- Find the number
- Look at the number to its right.
- 4 or less, just ignore
- 5 or more, add 1 more.
Example 1:
Round off 4 785 to the nearest 100.
Digit 7 is in the hundreds place.
Digit 8 is to its right.
Since 8 is more than 5, you need to add 1 to 7 to make it 8.
You need to convert digit 8 and 5 into 0 since you are rounding the numbers to the nearest 100.
Your answer should be 4 800.
Example 2:
Round off 24 385 to the nearest 1000.
Digit 4 is in the thousands place.
Digit 7 is to its right.
Since 3 is less than 5, you just ignore.
Digit 4 remains the same and convert digit 3, 8, and 5 to 0 since you are rounding the numbers to the nearest 1000.
Your answer should be 24 000.
Estimation
Estimation is used to predict the answer to a calculation. However, you need to round numbers to make your calculations easier and quicker to approximate your answer.
Example 1:
How do we estimate 11 x 13?
Round off 11 to the nearest 10.
10 x 13 = 130.
Example 2:
Estimate 115 x 79.
Round off 79 to the nearest 10, that is, 80 and 115 to the nearest 100, that is, 100
100 x 80 = 800