Adding and Subtracting Fractions - Unlik

What is adding and subtracting fractions?
Adding and subtracting fractions is the skill of ensuring the fractions in a calculation have common denominators so that the addition or subtraction can be carried out.

A fraction is a numerical quantity that is not a whole number (integer) but can be expressed as one integer divided by another. The division is represented by a horizontal line.

The integer on the top of the line is called the numerator.

The integer underneath the line is called the denominator.

2. We need a common
denominator to add
these fractions.

3. 7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
We need a common
denominator to add
these fractions.

4. 7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
The first number IN COMMON
that appears on both lists
becomes the common denominator

5. x 2
x 2
X 7
x 7
7
6
7 + 6 = 13
13

6. We need a common
denominator to add
these fractions.
5, 10, 15, 20, 25, 30, 35, 40, 45
7, 14, 21, 28, 35, 42, 49, 56, 63

7. x 7
x 7
X 5
x 5
15
7
15 + 7 = 22
22

8. We need a common
denominator to add
these fractions.
7, 14, 21, 28, 35, 42, 49, 56, 63
8, 16, 24, 32, 40, 48, 56, 64, 72

9. x 7
x 7
x 8
x 832
21
32 + 21 = 53
53

10. We need a common
denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27
5, 10, 15, 20, 25, 30, 35, 40, 45

11. X 3
x 5
x 5
x 3
9
10
9 + 10 = 19
19

12. We need a common
denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33
11, 22, 33, 44, 55, 66, 77…

13. x 11
x 11
X 3
x 315
22
15 + 22 = 37
37

14. We need a common
denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27
6, 12, 18, 24,…

15. x 1
x 1
X 2
x 24
1
4 + 1 = 5
5

16. We need a common
denominator to add
these fractions.
11, 22, 33, 44, 55, 66, 77…
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72

17. x 11
x 11
X 6
x 6
18
11
29
18 + 11 = 29

18. We need a common
denominator to add
these fractions.

19. We need a common
denominator to add
these fractions.
9, 18, 27, 36, 45, 54, 63, 72, 81
5, 10, 15, 20, 25, 30, 35, 40, 45

20. 9, 18, 27, 36, 45, 54, 63, 72, 81
5, 10, 15, 20, 25, 30, 35, 40, 45
The first number IN COMMON
that appears on both lists
becomes the common denominator

21. x 5
x 5
x9
x 9
36
35
36 + 35 = 71
71
36 + 35 = 71

22. We need a common
denominator to add
these fractions.
12, 24, 36, 48, 60, 72, 84, 96
8, 16, 24, 32, 40, 48, 56, 64, 72, 79, 80, 88, 96

23. x 3
x 3
x 2
x 2
19
10 + 9 = 19
9
10

24. 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
We need a common
denominator to
subtract a fraction
from another.
11, 22, 33, 44, 55, 66, 77…

25. x 5
x 5
x 11
x 11
4
15 - 11 = 4
15
11

26. We need a common
denominator to
subtract one fraction
from another.
2, 4, 6, 8, 10, 12, 14, 16, 18, 20 …
10, 20, 30…

27. x 1
x 1
x 5
x 5
2
5 – 3 = 2
5
3

28. Try These
A
F
EB
C
D

29. Answers On Next Slide
•Each click on the next slide
reveals an answer.
•Check your papers.
•If you discover an incorrect
answer, be able to explain
your mistake.

30. Try These
A
F
EB
C
D
17
27
19
20
10
9
41
28
26
21
13
12