Changing Denominators

What is the bottom number of a fraction called?

• numerator

• factor

• denominator

• sum

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

How can you find a common denominator?

• Add the denominators together

• Pick your favorite number

• Find a common multiple for the two denominators

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

Which of these numbers could NOT be a common denominator for these two fractions?
2/4   and   3/8

• 32

• 12

• 8

• 24

Adding & Subtracting Fractions with

UNLIKE Denominators

• I'm ready to try

• Let's do this!

• I'm not sure about these.

What must you have to add and subtract fractions?

• Common numerators

• Different numerators

• Different denominators

• Common denominators