# 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

1) 6       2) 0
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

1) 5.5       2) 0.5
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

1) 3.43      2) 8.48
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

1) 0.727      2) 83.768
3) 15.831      4) 7.001
5) 82.330      6) 0.010
7) 36.276      8) 0.827
9) 6.499      10) 0.995

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