Fractions (addition, subtraction, rounding, fraction of amounts).pptx

1. FUNCTIONAL
SKILLS MATH

2. Today!
• Starter: Brief discussion about
decimals.
• Tutorial: Fractions
(introduction, simplification,
addition, subtraction,
multiplication and division)
• Tutorial continued (comparison,
fraction of amounts, one number
as a fraction of another, round
and estimate)
• Extension activity – practice
worksheets

3. Any questions?
Any confusions?
Any problems?
You should already know how to:
✓ read, write, order and compare
decimals
✓ add, subtract, multiply and divide
decimals with up to 2 decimal places
✓ multiply and divide decimals by 10
and 100.
You should also know:
• order, approximate and compare
decimals
• calculate with decimals with up to 3
decimal places
DECIMALS.

4. Fractions

5. Fractions
Fractions are split into the top (called the numerator) and the
bottom (called the denominator). The bottom shows the number
of total parts and the top shows the number of parts of the total
there are. A fraction is just a division.

6. Equivalent fractions
Some fractions, even though they are
written differently, give the same
amount. These are equivalent
fractions, for example:
1/2 = 2/4 = 3/6 = 4/8 = 5/10
1/4 = 2/8
1/3 = 2/6 = 3/9
You find equivalent fractions by
multiplying or by dividing the
numerator and denominator of a
fraction by the same number.

7. Fraction in its lowest terms

8. Types of Fractions
Proper
Improper
Mixed Numbers

9. Mixed Fractions or Improper Fractions
We can use either an improper fraction or a mixed
fraction to show the same amount.

10. Converting Improper
Fractions to Mixed
Fractions
To convert an improper
fraction to a mixed fraction,
follow these steps:
•Divide the numerator by the
denominator.
•Write down the whole
number answer
•Then write down any
remainder above the
denominator.

12. Converting Mixed Fractions to Improper Fractions
To convert a mixed fraction to an improper fraction, follow these steps:
•Multiply the whole number part by the fraction's denominator.
•Add that to the numerator
•Then write the result on top of the denominator.

14. Adding and Subtracting
Fractions
To add and subtract fractions, it
usually helps to get rid of any
mixed numbers first, so mixed
numbers should first be
converted into improper fractions
OR you can work with the same
form.
You have to make sure the
denominators are the same.
Once you have a common
denominator, you then
add/subtract) the top numbers
only.
Example:
Calculate 𝟐
𝟏
𝟔
− 𝟏
𝟏
𝟐
Rewrite as improper fraction:
𝟐
𝟏
𝟔
− 𝟏
𝟏
𝟐
=
𝟏𝟑
𝟔
−
𝟑
𝟐
Find a common denominator:
𝟏𝟑
𝟔
−
𝟑
𝟐
=
𝟏𝟑
𝟔
−
𝟗
𝟔
Subtract the top line:
𝟏𝟑
𝟔
−
𝟗
𝟔
=
𝟏𝟑 − 𝟗
𝟔
=
𝟒
𝟔
=
𝟐
𝟑

16. Try the skill

17. Multiplying Fractions
Multiplying fractions is simple, you just multiply the top number and
the bottom number separately. You can cancel down the fraction first
if it helps.

18. Dividing Fractions
Dividing fractions is easier than it looks if you remember a simple trick.
‘You can turn the second fraction upside down and then multiply them
together.’

19. Activity
Work these out and then simplify your answers:
1)
3
5
×
6
7
2)
4
6
×
7
9
3)
2
5
÷
4
3
4)
2
3
−
4
6
5)
5
7
+ 1
9
12

20. Fraction of Amounts
To write one quantity as a fraction of another, put the
first quantity on the top of the fraction, and the second
quantity on the bottom.

22. Practice!
1. Write the following as fractions.
a. 6 out of 20
b. 14 out of 21
c. 24 out of 36
d. 25 out of 35
2. In a safety test, a car scored 35 points out of a possible 40.
Write this as a fraction in its simplest form.

27. One number as a fraction of another

30. An estimate is important when we do not need an exact answer, but we want the
estimate to be as close as possible to the real answer.
The first thing you always need to do before estimating fractions is to round each
fraction either to the nearest 0, 1/2, or 1.
ROUND AND ESTIMATE FRACTIONS

31. Closer to 0 – Each numerator is much less than half the denominator, so the
fraction is closer to 0.
Closer to ½ - Each numerator is about half than half the denominator, so the
fraction is closer to 1/2.
Closer to 1 - Each numerator is much more than half the denominator, so the
fraction is closer to 1.

32. Example #1
Estimate 3/7 + 5/9
Notice that 3/7 is close to 1/2 and 5/9 is also close to 1/2.
Therefore, an estimate for 3/7 + 5/9 is 1/2 + 1/2 = 1
Example #2
Estimate 1/12 + 3/5
Notice that 1/12 is close to 0 and 3/5 is close to 1/2.
Therefore, an estimate for 1/12 + 3/5 is 0 + 1/2 = 1/2
Example #3
Estimate 9/10 + 19/20
Notice that 9/10 is close to 1 and 19/20 is close to 1
Therefore, an estimate for 9/10 + 19/20 is 1 + 1 = 2

33. Q1:
Estimate
5
6
÷
7
8
by rounding each fraction to the nearest half.
Q2.
By rounding each term to a whole number, estimate 54
5
÷ 2
1
2
Q3:
Two children are making a cake. One has 3
1
3
cups of flour and
the other has 4
5
8
cups of flour. Estimate how many cups of flour
they have together by rounding to the nearest half.
Try the skill