Chapter Review - 4. Multiply and Divide Fractions - Glencoe Math: Course 1, Volume 1

We are asked to describe what it means to multiply and divide fractions. Let's start with multiplication.

Multiplication of Fractions

We can think of multiplication of fractions as calculating a portion of a fraction. Let's take a look at an example. 1/2 * 3/5 When we multiply 35 by 12, we take a half of it. We multiply fractions on a daily basis. Here is an example of a real-life problem for the product.

We need powdered sugar to make cookies. A bag of powdered sugar is 35 pound. We have only a 12 bag left. How much sugar do we have left?

We can solve the problem if we multiply the fractions. The remaining sugar weighs 12 * 35 pounds. Let's calculate this product! Remember that when we multiply fractions, we multiply the numerators and the denominators separately. 1/2 * 3/5 &= 1* 3/2 * 5 [0.8em] &= 3/10 We have 310, or 0.3, pounds of powdered sugar left.

Division of Fractions

Division of fractions, on the other hand, is the process by which we split a fraction into equal fractional parts. With division we determine how many of those parts we will have. Let's take a look at an example. 3/4 ÷ 1/8 We can think up a real life problem for this quotient.

Sasha is making ribbon bows for his Christmas presents. Each bow takes 18 meter of ribbon to make. How many ribbons can Sasha make with 34 meter of ribbon?

This time we want to know how many 18-meter sections we can get from 34 meter of ribbon. This means we need to divide the numbers. 3/4 ÷ 1/8 Let's calculate the quotient! Remember that to divide by a fraction, we multiply the dividend by the reciprocal of the divisor. 3/4 ÷ 1/8 = 3/4 * 8/1 Next, we multiply the fractions and simplify the resulting expression. We can use the greatest common factor (GCF) to make the calculations easier.

3/4 * 8/1

MultFrac

Multiply fractions

3* 8/4* 1

SplitIntoFactors

Split into factors

3* 2 * 4/4* 1

CrossCommonFac

Cross out common factors

3* 2 * 4/4* 1

SimpQuot

Simplify quotient