Fraction Operations

Bell work. Draw how you would show 3/8 of a candy bar being added to 1/4 of a candy bar. Draw 1/4 of a candy bar subtracted from 3/8 of a candy bar.

1. Addition 3/8 + 1/4 = 5/8

2. Subtraction 3/8 – 1/4 = 1/8

3. Multiplication 3/8 of 1/4 = 3/8 x 1/4= 3/32

Yellow equals 1/4. Cross hatched yellow equals 3/8 of 1/4. Each small rectangle is 1/32 of the whole (4 sections each split into 8 parts). The 3 cross-hatched yellow rectangles hence equal 3/32 of the whole.

4. Division 3/8 ¸ 1/4 = 1 ½

This means how many 1/4s in 3/8s. As shown there are 1 ½ one-fourths in three eighths.

Rules:

1. Addition

Must have denominators the same. If unlike denominators, find least common denominator. Write equivalent fractions with that denominator. Add numerators. Denominator stays the same.

E.g.

2. Subtraction

Must first have denominators the same. If unlike denominators find least common denominator. Write equivalent fractions with that denominator. Subtract second numerator from first. Denominator stays the same.

E.g.

3. Multiplication

Multiply numerators and denominators.

E.g.

4. Division

Invert divisor (the second fraction) then multiply.

E.g.

5. Mixed numbers

With addition and subtraction, you can add or subtract the whole numbers separate from the fractions. With multiplication and division, you must convert the mixed number to an improper fraction first.

E.g.