1. &
dding
ubtracting
ractions

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

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

4. LCM = least common multiple!
Count by 2's
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
Count by 7's
7, 14, 21, 28, 35…
The first number IN COMMON
that appears on both lists
becomes the common denominator
LCM = least common multiple!

5. 7 6 13 = = + 7 + 6 = 13 x 7 X 7 x 2 x 2 Make equivalent fractions.
Add the numerators = +
7 + 6 = 13
x 2 13

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

7. 15 7 22 = + = 15 + 7 = 22 x 5 X 5 x 7 x 7 Make equivalent fractions.
Add the numerators =
x 7
= 22 22

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

9. 32 21 53 32 + 21 = 53 = + = x 8 x 8 x 7 x 7 Make equivalent fractions.
Add the numerators
x 7 +
= 53 =
x 7 53

10. Try These A D E B F C

11. Try These 10 9 17 27 A D 41 28 13 12 B E 19 20 26 21 C F