Finding a Common Denominator

How do you find the common denominator when adding fractions with unlike denominators?

• By multiplying the denominators together

• By finding the greatest common factor

• By finding the least common multiple

• By adding the denominators together

The bottom number of a fraction is called the ______________

What must you do first in order to add or subtract fractions with unlike denominators?

• add the numerators

• add the denominators

• find a common denominator

• find a common numerator

What number could be a common denominator for these three fractions?
1/2   and   1/3   and   1/4

• 9

• 8

• 12

• 6

What must you have to add and subtract fractions?

• Common numerators

• Different numerators

• Different denominators

• Common denominators

• 1/12
• 1
• 2/35
• 23/25

What is the least common denominator for 3 and 4?

• 6

• 4

• 3

• 12

What is the least common denominator for 7 and 2?

• 12

• 14

• 7

• 6

Add the following fractions by finding equivalent fractions with like denominators.

• 1/6

• 4/12

• 2/3

• 5/12

3/9 + 4/9

• 7/18

• 7/9

• 12/9

• 12/81