11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Working with Decimals
Decimal Scales
Decimal Decimal NumbersNumbers
ww
w.m
ath
srevis
ion
.com
Multiplying and Dividing by 10, 100, 1000
Multiplying and Dividing by a single Digit
Rounding to 1 Decimal Place
Addition and Subtraction
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com
1. Find the missing value
2. Calculate of 6000
3. What is the next three numbers in the sequence 9, 15, 21, 27, ...., ...., .... 4. Round 72 to the nearest 10
3 ?=4 20
20%
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1.1. Understand what a decimal Understand what a decimal number is.number is.
1. We are learning what a decimal number is. Write down the decimal number represented by a fraction diagram.
Decimal Decimal NumbersNumbers
2.2. Write down the decimal Write down the decimal number represented by a number represented by a fraction diagram.fraction diagram.
Writing DecimalsMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
When you take a When you take a single unitsingle unit and divide it and divide it into 10 bitsinto 10 bits, , what we then have are what we then have are
decimal fractionsdecimal fractions of a whole number of a whole number
Writing Decimals
Imagine, 1 bar of chocolate as our UNIT of measure.
1 (of 1 bar)
10
or 0.1
1
0.110 1. 0
0.1 0.40.2 0.3 0.5
0.6 0.90.7 0.8 1.0
means ten
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Writing Decimals
Example : Write down the decimal number represented by the shaded area.
(a)
(b)
0.3
3 "which means 3 tenths = "
10
0.5
5 1 "which means 5 tenths = = "
10 2
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Writing Decimals
Example : Write down the decimal number represented by the diagram.
(a) (b)
(c) (d)
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
We can take one bit of the chocolate bar We can take one bit of the chocolate bar and split it into 10and split it into 10
Writing Decimals
0.10.01
1st Decimal place
2nd Decimal place
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Writing Decimals
Example : Write down the decimal number represented by the diagram.
(a) (b)
(c) (d)
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Exercise 1
Ch2 (page 25)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Writing DecimalsMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com 1. Find the perimeter of the shape
2. Calculate 30% of 900
3. Find the area of the rectangle
6cm in length by 4 cm wide.
4. Name the shape.
3cm
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1.1. Understand the steps to Understand the steps to work out any decimal scale work out any decimal scale to 2 decimal places.to 2 decimal places.
1 We are learning the steps to read decimal scales.
Decimal Decimal NumbersNumbers
2.2. Solve problems by working Solve problems by working out scales. out scales.
Reading ScalesMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
You must work out what number goes next to each markon the scale.
Step 1: Count the number of steps between numbers.
In this case it takes 10 steps to get from 0.0 to 1.0cm.
Step 2: Do the division
“ the difference between numbers”by the step number
1.0 ÷ 10 = 0.1cm
ww
w.m
ath
srevis
ion
.com
0.0 1.0cm 2.0cm
0.10.2
0.30.4
0.50.6
0.70.8
0.9
1.11.2
1.31.4
1.51.6
1.71.8
1.9
Decimal Decimal NumbersNumbers
Reading ScalesMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Find the values of the arrows
8.3 8.8 9.5 9.8
8 9cm 10cm
Step 1: Count the number of steps between numbers.
In this case it takes 10 steps to get from 8 to 9cm.
Step 2: Do the division
“ the difference between numbers”by the step number
1 ÷ 10 = 0.1cm9-8=1
10
Decimal Decimal NumbersNumbers
Reading ScalesMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
You must work out what number goes next to each markon the scale.
Step 1: Count the number of steps between numbers.
In this case it takes 10 steps to get from 3.00cm to 3.10cm.
Step 2: Do the division
“ the difference between numbers”by the step number
0.1 ÷ 10 = 0.01cm
ww
w.m
ath
srevis
ion
.com
3.00cm 3.10cm 3.20cm
3.013.02
3.033.04
3.053.06
3.073.08
3.09
3.113.12
3.133.14
3.153.16
3.173.18
3.19
Decimal Decimal NumbersNumbers
Reading Harder ScalesMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Step 1: Count the number of steps between numbers.
In this case it takes 10 steps to get from 12.00cm to 12.10cm.
Step 2: Do the division
“ the difference between numbers”by the step number
0.1 ÷ 10 = 0.01cm
ww
w.m
ath
srevis
ion
.com
12.00cm 12.10cm 12.20cm
Decimal Decimal NumbersNumbers
Reading Harder Scales
12.03 12.08 12.14 12.19
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Exercise 2Ch12 (page 28)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Reading ScalesMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com 1. Name the part of the circle.
2. Calculate 60% of 300
o3. I f I am f acing North and turn 90 clockwise, which direction am I f acing
4. How many lines of symmetry has the shape.
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1. We are learning how to round to 1 decimal place.
Decimal Decimal NumbersNumbers
1.1. Remember steps to Remember steps to round round to 1 decimal place.to 1 decimal place.
Rounding to 1 decimal placeMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
ww
w.m
ath
srevis
ion
.com
8.2cm 8.3cm 8.4cm
Decimal Decimal NumbersNumbers
8.24 8.28 8.35
Rounding to 1 decimal place
Find the values of the arrows.
Is 8.24 nearer to 8.2 or 8.3 ? 8.2Is 8.28 nearer to 8.2 or 8.3 ? 8.3Is 8.35 nearer to 8.2 or 8.3 ? Neither
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Rounding to 1 decimal place
If the 2nd decimal place is 0,1,2,3,4 - leave 1st decimal place as it is
Example : Round the numbers to 1 decimal place
(a) 9.04 (b) 18.08 (c) 24.25
(d) 12.73 (e) 102.09 (f) 2636.55
If the 2nd decimal place is 5,6,7,8,9 - add 1 to 1st decimal place
The rules for rounding to 1 decimal place are:
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Exercise 3Ch2 (page 30)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Rounding to 1 decimal placeMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com
1. 13 x 7
2. Calculate 23 x 10
3.
4. Find the missing number
3 of 804
1, 1, 2, 3, 5, 8, ...., ...., ....
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1. We are learning how to add and subtract decimal numbers.
1. Understand that you must keep the decimal point lined up when adding and subtracting decimal numbers.
Decimal Decimal NumbersNumbers
2. Show all working.
Add and Subtract DecimalsMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Example 1 : Calculate 7.8 + 0.92
When you add or subtract decimal numbers, it is important to line-up the decimal points.
Add and Subtract Decimals
7.80
+0.928 .721
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Example 1 : Calculate 4 – 0.84
When you add or subtract decimal numbers, it is important to line-up the decimal points.
Add and Subtract Decimals
3 9 1 4 . 0 0
- 0
. 8 43
. 1 6
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Example 1 : Find the value x cm and y cm
Add and Subtract Decimals
3. 25
-
2.201. 05
2.1cm3.91cm
x cm
2. 10
+ 3.916 .011
x cm y cm
y cm3.25cm
2.2cm
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Exercise 4Ch2 (page 32)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Add and Subtract DecimalsMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com
1. 46 x 3
2. Find the missing value
3.
4. Calculate the value of the missing angle.
35 ?=50 10
1 of 4907
40 o
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1.1. Understand the simple rules Understand the simple rules to multiply and divide to multiply and divide decimal numbers.decimal numbers.
1 We are learning how to multiply and divide decimal numbers by 10, 100, 1000.
2.2. Be able do calculations.Be able do calculations.
Decimal Decimal NumbersNumbers
Multiplying & Dividing by 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
To multiply a decimal number by 10, Simply move point 1 place to the right:
e.g. 2.55 x 10 = 25.5 point is moved 1 place to right
Multiplying by 10, 100, 1000
To multiply a decimal number by 100, Simply move point 2 places to the right:
e.g. 1.02 x 100 = 102.0 point is moved 2 places to right
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
To multiply a decimal number by 1000, Simply move point 3 places to the right:
e.g. 34.567 x 1000 = 34 567 point is moved 1 place to right
Multiplying by 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Example : Multiply 1.8574 by 10, 100, 1000
10 x 1.8574 =
100 x 1.8574 =
1000 x 1.8574 =
18.574
185.74
1857.4
Multiplying by 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Ex 5First Column in each
Question ONLYCh2 (page 35)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Multiplying & Dividing y 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
To divide a decimal number by 10, Simply move point 1 place to the left:
e.g. 89 ÷ 10 = 8.9 point is moved 1 place to left
Dividing by 10, 100, 1000
To divide a decimal number by 100, Simply move point 2 places to the left:
e.g. 199 ÷ 100 = 1.99 point is moved 2 places to left
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
To divide a decimal number by 1000, Simply move point 3 places to the left:
e.g. 35 837 ÷ 1000 = 35.837 point is moved 3 places to the left
Dividing by 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Example : Divide 45 024 by 10, 100, 1000
45 024 ÷ 10 =
45 024 ÷ 100 =
45 024 ÷ 1000 =
4502.4
450.24
45.024
Dividing by 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Ex 6First Column in each
Question ONLYCh2 (page 35)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Multiplying & Dividing y 10, 100, 1000MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Starter QuestionsStarter Questionsw
ww
.math
srevis
ion
.com 1. 320 8
2. Calculate 20% of 360
3. Calculate 72 - 58
4. Calculate the value of the missing angle.
57o
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Learning IntentionLearning Intention Success CriteriaSuccess Criteria
1. We are learning how to multiply and divide a decimal number by a single Digit.
1. Understand how to multiply and divide a decimal number by a single Digit.
Decimal Decimal NumbersNumbers
2. Show appropriate working.
Multiplication & Division by a Single DigitMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
When multiplying by a single digit the decimal point always stays in line.
Example : Calculate 23.68 x 7
Multiplication & Division by a Single Digit
2 4 5
23.68
x 7165 .76
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
When dividing by a single digit the decimal point always stays in line.
Example : Calculate 17.16 ÷ 6
Multiplication & Division by a Single Digit
1 5 3
2 . 8 6 6 17. 16
MNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww
w.m
ath
srevis
ion
.com Example : Copy and complete.
3.5 x 6 18.43 x 4 76.97 x 6
6.52 ÷ 2 95.05 ÷ 5 204.84 ÷ 6
Decimal Decimal NumbersNumbers
Multiplication & Division by a Single DigitMNU 2-03b MNU 2-04a
11 Apr 202311 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.
Now try Ex 7 & 8Ch2 (page 37)
ww
w.m
ath
srevis
ion
.com
Decimal Decimal NumbersNumbers
Multiplication & Division by a Single DigitMNU 2-03b MNU 2-04a