Ray's New Practical Arithmetic · Arts. 115–118 · Unit 10: Fractions
58. Multiplying fractions
Goal: Your child multiplies fractions, mixed numbers and whole numbers by fractions, simplifies compound fractions, and uses cancellation.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
Multiplication of fractions with worked examples, the rule and remarks, problems, finding a fraction of a whole number, compound fractions, and miscellaneous cost problems with answers.
The lesson, step by step
Warm-up
Mental: 1/2 of 8? 1/3 of 12? 3/4 of 12?
The rule
Read:
Multiplication of Fractions is the process of finding the product of two or more fractional numbers.
Multiply together the numerators of the given fractions for the numerator of the product.
Multiply together the denominators of the given fractions for the denominator of the product.
Example: 2/3 × 3/4 = 6/12 = 1/2. Fold paper to show 2/3 of 3/4.
Remarks
Read:
Express integers in the form of fractions
Reduce mixed numbers to improper fractions
Indicate the operation and apply the Rule for Cancellation wherever it is practicable
Compound fractions
Read:
Compound fractions (Art. 99) are reduced to simple fractions by multiplication.
Example: 1/2 of 2/3 of 3/4 = 6/24 = 1/4, or cancel first.
Guided practice
Do a few multiplication problems together, then one of the cost problems that follow ("What will be the cost ...").
Independent practice
Your child does about ten multiplication problems, five compound fractions and five cost problems.
Check and wrap-up
Answers are printed for the compound-fraction and cost problems. For the drill problems without answers, check by cancelling first and multiplying again. Mental: 2/3 of 9? 3/5 of 20?