Adding and Subtracting Fractions with Common Denominator

When adding and subtracting fractions, what needs to be the same?

• the numerator

• the denominator

• nothing

• everything

When adding or subtracting fractions with unlike denominators, what is the first step?

• Add the numerators

• Add the denominators

• Find a common denominator

When adding fractions with like denominators, the denominators....

• stay the same

• are added together

How can you find a common denominator?

• Add the denominators together

• Pick your favorite number

• Find a common multiple for the two denominators

Mr. Smith buys 5/8 pound of red grapes and 2/8 pound green grapes. How many pounds did Mr. Smith buy?

• 7/8 pound

• 3/8 pound

• A
• B
• C
• D

2/7 + 3/7 = 

• 4/7

• 5/7

• 5/14

After changing the denominator, what do you need to do to the numerator?

• Nothing

• Multiply the numerator by the same number as the denominator

• Double it

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

• 3

• 4

• 7

• 12

What number could be a common denominator for these two fractions?
1/5   and   5/6?

• 30

• 11

• 6

• 5