Add and Subtract Fractions with Unlike Denominators #1

Add and Subtract Fractions with Unlike Denominators

To add 1/2 + 3/7 we must first find a common denominator using least common multiples.

First, make your chart

Multiple Choice

What must you first find to be able to add or subtract fractions with unlike denominators?

• greatest common factor

• common denominator

• least common multiple

Now, fill in your chart by multiplying each denominator.

Stop when you have found the lowest common multiple.

Multiple Choice

What do you use to find common denominators?

• greatest common factors

• least common factors

• greatest common multiples

• least common multiples

Multiply each fraction so that the denominators have your least common multiples for your least common denominators.

Add only your numerators. Your denominators stay the same.

Multiple Choice

What is the least common denominators for 7/8 - 4/5?

• 30

• 48

• 15

• 40

Multiple Choice

What is the least common denominator for 4/6 + 2/9?

• 18

• 36

• 45

• 12