1. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Working with Decimals
Decimal Scales
Rounding to nearest whole number
Rounding to 1 Decimal Place
Addition and Subtraction
8-Jan-18
Created by Mr. Lafferty Maths Dept.

2. Created by Mr. Lafferty Maths Dept.
Starter Questions
8-Jan-18
Created by Mr. Lafferty Maths Dept.

3. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Writing Decimals
Learning Intention
Success Criteria
1. We are learning what a decimal number is. Write down the decimal number represented by a fraction diagram.
Understand what a decimal number is.
2. Write down the decimal number represented by a fraction diagram.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

4. Decimal Numbers www.mathsrevision.com means ten Writing Decimals
When you take a single unit
and divide it into 10 bits,
what we then have are
decimal fractions of a whole number
Imagine, 1 bar of chocolate as our UNIT of measure.
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
or 0.1
8-Jan-18
Created by Mr. Lafferty Maths Dept.

5. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Writing Decimals
Example : Write down the decimal number
represented by the shaded area.
(a)
(b)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

6. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Writing Decimals
Example : Write down the decimal number
represented by the diagram.
(a)
(b)
(c)
(d)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

7. Decimal Numbers www.mathsrevision.com Writing Decimals
We can take one bit of the chocolate bar
and split it into 10
1st Decimal place
0.01
0.1
2nd Decimal place
8-Jan-18
Created by Mr. Lafferty Maths Dept.

8. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Writing Decimals
Example : Write down the decimal number
represented by the diagram.
(a)
(b)
(c)
(d)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

9. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Writing Decimals
Now try TJ2a
Ex 1
Ch5 (page 37)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

10. Created by Mr. Lafferty Maths Dept.
Starter Questions
3cm
8-Jan-18
Created by Mr. Lafferty Maths Dept.

11. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Scales
Learning Intention
Success Criteria
1 We are learning the steps to read decimal scales.
Understand the steps to work out any decimal scale to 2 decimal places.
2. Solve problems by working out scales.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

12. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Scales
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
0.1
0.0cm
1.0cm
2.0cm
You must work out what number goes next to each mark
on the scale.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

13. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Scales
Find the values of the arrows
8cm
9cm
10cm
8.3
8.8
9.5
9.8
8-Jan-18
Created by Mr. Lafferty Maths Dept.

14. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Harder Scales
3.02
3.04
3.05
3.06
3.07
3.08
3.09
3.11
3.12
3.13
3.14
3.15
3.16
3.17
3.18
3.19
3.01
3.03
3.00cm
3.10cm
3.20cm
You must work out what number goes next to each mark
on the scale.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

15. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Harder Scales
12.00cm
12.10cm
12.20cm
12.03
12.08
12.14
12.19
8-Jan-18
Created by Mr. Lafferty Maths Dept.

16. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Scales
Now try TJ2a
Ex 2
Ch5 (page 41)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

17. The answer to the question is
Starter Questions
The answer to the question is 60
Write down as many questions as you can
8-Jan-18
Created by Mr. Lafferty Maths Dept.

18. Created by Mr. Lafferty Maths Dept.
Rounding
Learning Intention
Success Criteria
1. Use previous knowledge to help round to any number to the nearest whole number.
1. We are learning to round to the nearest whole number.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

19. Rounding 2.4 2 2.7 3 www.mathsrevision.com 2.5 3
All to do with the number 5
Rounding
Rounding to the nearest whole number we look at
the first decimal place :
2.4
since 4 is less than 5 nearest whole number is 2
2.7
since 7 is more than 5 nearest whole number is 3 ?
2.5
since 5 is not less than 5 nearest whole number is 3
8-Jan-18
Created by Mr. Lafferty Maths Dept.

20. Rounding 432.67 433 www.mathsrevision.com 596.55 597 13.05 13
All to do with the number 5
Rounding
Round the following to the nearest whole number.
432.67
433
596.55
597
13.05 13
8-Jan-18
Created by Mr. Lafferty Maths Dept.

21. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Reading Scales
Now try TJ2a
Ex 3
Ch5 (page 44)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

22. Created by Mr. Lafferty Maths Dept.
Starter Questions
8-Jan-18
Created by Mr. Lafferty Maths Dept.

23. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Rounding to 1 decimal place
Learning Intention
Success Criteria
We are learning how to round to 1 decimal place.
1. Remember steps to round to 1 decimal place.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

24. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Rounding to 1 decimal place
Find the values of the arrows.
8.2cm
8.3cm
8.4cm
8.24
8.28
8.35
Is 8.24 nearer to 8.2 or 8.3 ?
8.2
Is 8.28 nearer to 8.2 or 8.3 ?
8.3
Is 8.35 nearer to 8.2 or 8.3 ?
Neither
8-Jan-18
Created by Mr. Lafferty Maths Dept.

25. Decimal Numbers www.mathsrevision.com Rounding to 1 decimal place
The rules for rounding to 1 decimal place are:
If the 2nd decimal place is 0,1,2,3,4 - leave 1st decimal place as it is
If the 2nd decimal place is 5,6,7,8,9 - add 1 to 1st decimal place
Example : Round the numbers to 1 decimal place
9.04 (b) (c) 24.25
(d) (e) (f)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

26. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Rounding to 1 decimal place
Now try TJ2a
Ex 4
Ch5 (page 46)
8-Jan-18
Created by Mr. Lafferty Maths Dept.

27. Created by Mr. Lafferty Maths Dept.
Starter Questions
8-Jan-18
Created by Mr. Lafferty Maths Dept.

28. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Add and Subtract Decimals
Learning Intention
Success Criteria
1. Understand that you must keep the decimal point lined up when adding and subtracting decimal numbers.
1. We are learning how to add and subtract decimal numbers.
2. Show all working.
8-Jan-18
Created by Mr. Lafferty Maths Dept.

29. Decimal Numbers 8 . 7 2 www.mathsrevision.com
Add and Subtract Decimals
When you add or subtract decimal numbers,
it is important to line-up the decimal points.
Example 1 : Calculate
8-Jan-18
Created by Mr. Lafferty Maths Dept.

30. Decimal Numbers 3 . 1 6 www.mathsrevision.com
Add and Subtract Decimals
When you add or subtract decimal numbers,
it is important to line-up the decimal points.
Example 1 : Calculate 4 – 0.84
8-Jan-18
Created by Mr. Lafferty Maths Dept.

31. Created by Mr. Lafferty Maths Dept.
Decimal Numbers
Add and Subtract Decimals
Example 1 : Find the value x cm and y cm
3.91cm
2.1cm
y cm
3.25cm
2.2cm
x cm
y cm
x cm
8-Jan-18
Created by Mr. Lafferty Maths Dept.

32. Have you updated your Learning Log ?
Decimal Numbers
Add and Subtract Decimals
Now try TJ2a
Ex 5
Ch5 (page 48)
Are you on Target ?
I can ?
8-Jan-18
Created by Mr. Lafferty Maths Dept.