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Addition and Subtraction
Involving Fractions, decimals,
and mixed numbers
Lesson 1 (3rd 6 Weeks)
TEKS 6.2B
Adding/Subtracting Decimals
• Line up decimals, add zeros at the
end of the numbers so each one
has the same number of decimal
places
• Add & subtract like whole numbers,
regrouping as needed.
• Bring decimal straight down in the
answer.
EX:
• Find the difference between 33.5
and 8.35
2
4
1
1
33.5
0
- 8.35
2 5 .15
+/- Fractions & Mixed
Numbers
• If the fractions have the same
denominator, add/subtract the
numerators and use the same
denominator.
• EX:
6 + 8 = 6 + 8 = 14
17
17 17
17
• If the fraction have unlike
denominators, rewrite them as
fractions with a common
denominator. Then add/subtract the
numerators and use the common
denominator.
• When adding/subtracting mixed
numbers the whole-number and
fractional parts may need to be
regrouped.
• If necessary, simplify the answer.
EX:
+
1x1=
8x1=
1
8
3x2=
4x2=
6
8
7
8
1+6=7
EX:
2 x 8 = 16
3 x 8 = 24
-
5 x 3 = 15
8 x 3 = 24
1
24
16 – 15 = 1
EX:
10 x 2 = 20
15 x 2 = 30
-
2 x 5 = 10
6 x 5 = 30
10
10
1
÷
=
3
10
30
EX:
2
+
3
1x5= 5
4 x 5 = 20
2 x4= 8
5 x 4 = 20
5
13
20
EX:
21
3
18
=
1=
+
18
18
18
1 x 3 = 21
3
87 6 x 3 = 18
-
3
4x2= 8
9 x 2 = 18
13
4 18