Lesson 9- Rounding Decimals
Objective
At the end of this lesson, students should be able round decimal numbers to the nearest whole number, tenth, hundredth or thousandth.
Rounding a decimal means representing it by a number to which the decimal is nearest to.
Rounding a decimal numbers allows us to write the number in a way to suit our purposes. Decimals can be rounded to the nearest whole number, tenth, hundredth, thousandth, etc.
If we are to round to the nearest whole number:
a) 3.54 = 4 b) 3.49 = 3 c) 3.504 = 4 d) 3.497 = 3
A similar idea is what we use to round figures. Below are some examples:
Example 1
Round these decimal numbers to the nearest whole number.
a) 2.63 b) 13.429 c) 238.532
Solution
Example 2
Round to the nearest tenth (1 decimal place):
a) 4.829 b) 13.499 c) 6.952
Example 3
Round to the nearest hundredth (2 decimal places)
a) 4.826 b) 267.199 c) 10.841
Example 4
Round to the nearest thousandth (3d.p)
a) 2.8469 b) 18.2195 c) 9.1111
Solution
a) 2.8469 = 2.847
b) 18.2195 = 18.220
c) 9.1111 = 9.111
Unit 10 Lesson 9: Exercise 1
Round the following decimals to the nearest whole number
1) 5.8 2) 0.4
3) 9.764 4) 0.574
5) 29.671 6) 48.259
7) 300.28 8) 900.94
9) 66.511 10) 98.921
3) 10 4) 1
5) 30 6) 48
7) 300 8) 901
9) 67 10) 99
Unit 10 Lesson 9: Exercise 2
Round these decimals to the nearest tenth
1) 5.469 2) 0.512
3) 0.75 4) 0.42
5) 12.897 6) 10.957
7) 20.094 8) 49.913
9) 7.952 10) 3.518
3) 0.8 4) 0.4
5) 12.9 6) 11.0
7) 20.1 8) 49.9
9) 8.0 10) 3.5
Unit 10 Lesson 9: Exercise 3
Round to the hundredth (2 decimal places)
1) 3.426 2) 8.482
3) 5.734 4) 0.035
5) 59.261 6) 44.575
7) 50.108 8) 245.002
9) 98.217 10) 875.973
3) 5.73 4) 0.04
5) 59.26 6) 44.58
7) 50.11 8) 245.00
9) 98.22 10) 875.97
Unit 10 Lesson 9: Exercise 4
Round these decimals to 3 decimal places
1) 0.7268 2) 83.7681
3) 15.8306 4) 7.0005
5) 82.3297 6) 0.0098
7) 36.2764 8) 0.8266
9) 6.4992 10) 0.9946
3) 15.831 4) 7.001
5) 82.330 6) 0.010
7) 36.276 8) 0.827
9) 6.499 10) 0.995