Objective:
At the end of this lesson, students should be able to round decimals to the nearest whole number, tenth, hundredth or thousandth.
When you round a decimal, you represent it by a number that the decimal is closest to. Rounding enables you to write a number in a way that suits your purpose. Decimals can be rounded to the nearest whole number, tenth, hundredth, thousandth, etc.
Steps to follow when rounding decimals:
Quick reminder:
From previous knowledge acquired on the study of decimal number lines;
6.5 is half way between 6 and 7
6.54 is nearer to 7, because it is more than half way between 6 and 7.
6.49 is nearer to 6, because it is less than half way between 6 and 7.
6.501 is more than half way between 6 and 7.
6.498 is less than half way between 6 and 7.
Suppose we are to round these decimals the nearest whole number;
A similar approach is applied when rounding numbers.
Example 1
Round these numbers to their nearest whole number
a) 7.49 b) 18.91 c) 39.085
Example 2
Round to 1 decimal place (nearest tenth).
a)0.455 b) 8.99 c) 57.08
Solution
Example 3
Round to the nearest hundredth (2 decimal places)
a) 49.894 b) 12.899 c) 130.007
Solution
Example 4
Round to the nearest thousandth (3 decimal places)
a) 99.9985 b) 18.9063
Solution
Unit 10 Lesson 8: Exercise 1
Round these decimals to the nearest whole number.
Unit 10 Lesson 8: Exercise 2
Round to the nearest tenth.
Unit 10 Lesson 8: Exercise 3
Round these decimal numbers to 2 decimal places.
Unit 10 Lesson 8: Exercise 4
Round these to the nearest 1/1000 of a kilometer.
Unit 10 Lesson 8: Exercise 5
Write the decimal equivalent to each fraction to the nearest hundredth.