Ray's New Practical Arithmetic · Art. 130 · Unit 10: Fractions

62. Practice (aliquot parts)

Goal: Your child uses easy parts of a dollar (25 cents = 1/4, 12½ cents = 1/8, 33⅓ cents = 1/3) to work prices in the head.

⏱ About 35 minutes · 6 steps

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You'll need

  • The book
  • A slate, small whiteboard or scrap paper
  • A notebook and pencil

What's in the book

Practice: aliquot parts of 100 and of a dollar, a table of them, worked examples, and problems 1 to 24 on prices, with printed answers.

The lesson, step by step

  1. Warm-up

    Mental: How many quarters in a dollar? 8 eighths of a dollar is how many cents each? (12½.)

  2. The idea

    Read:

    An aliquot part is an exact divisor of a number.

    Go through the table: 50 cents is 1/2, 25 is 1/4, 20 is 1/5, 12½ is 1/8, 33⅓ is 1/3, 16⅔ is 1/6, 6¼ is 1/16 of a dollar.

  3. Work the book example

    Read:

    What will 24 yd. of muslin cost at 25 ct. a yd.?

    Since 25 ct. is ¼ of a dollar, the cost will be ¼ as many dollars as there are yards.

    24 ÷ 4 = $6.

  4. Guided practice

    Together:

    What will 80 gal. of wine cost at $2.37½ a gal.?

    What will 36 barrels of flour cost at $8.33⅓ a barrel?

    ($190 and $300.)

  5. Independent practice

    Your child does problems 4 to 16 using aliquot parts wherever possible.

  6. Check and wrap-up

    Answers are printed. Shop in your head: 16 items at 25 cents? 9 at 33⅓ cents? 24 at 12½ cents?

Tip

This is the old name for a skill shoppers still use. Encourage your child to look for the easy fraction before multiplying.

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