Adding and Subtracting
Fractions
Warm up
What is the lowest
common multiple of:
Find a the missing numbers
2
=
6
3 and 4
12
5
15
5 and 6
30
4 and 6
12
3
15
=
8
40
3 and 8
24
5 and 10
10
25
5
=
6
30
Adding and Subtracting
Fractions
Two rulers add three rulers is:
5 rulers
Four pens add five pens is: 9 pens
Two pens add Five rulers is: 7 Pieces of equipment
We can’t so this until we have a name
that describes both groups
When we add fractions we need them to have the same name
Adding and Subtracting
Fractions
2
3 = 5
+
7
7
7
2
4 = 6
+
9
9
9
1
3 = 4
+
11
11
11
Adding and Subtracting
Fractions
2
3 = 5
+
7
7
7
2
4 = 6
+
9
9
9
5
3 = 2
11
11
11
Adding and Subtracting
Fractions
We need to make sure the denominator of both fractions is the
same before we add or subtract
2
3 =
+
5
10
4
3
7
+
=
10
10
10
We need a number in the 5
and 10 times table to
use as our bottom
number- 10?
Adding and Subtracting
Fractions
We need to make sure the denominator of both fractions is the
same before we add or subtract
1
5 =
+
3
12
4
5
9
+
=
12
12
12
We need a number in the 3
and 12 times table to
use as our bottom
number- 12?
Adding and Subtracting
Fractions
We need to make sure the denominator of both fractions is the
same before we add or subtract
2
3 =
+
5
6
12
15
27
+
=
30
30
30
We need a number in the 5
and 6 times table to use
as our bottom number30?
Adding and Subtracting
Fractions
We need to make sure the denominator of both fractions is the
same before we add or subtract
7
2 =
8
3
21
16
5
=
24
24
24
We need a number in the 8
and 3 times table to use
as our bottom number24?
a)
b)
c)
d)
e)
7/8
8/12
7/9
7/10
2/3
a)
b)
c)
d)
e)
11/12
7/10
8/15
16/12 or 1 ¼
11/24
a)
b)
c)
d)
e)
1 7/12
1 5/56
29/30
29/52
1 1/10
a)
b)
c)
d)
e)
5/8
5/12
1/3
2/5
1/2
a)
b)
c)
d)
e)
7/20
8/21
23/36
9/22
71/126
Adding and Subtracting Fractions
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answers