Lesson 9

Workshop: Decimal Concepts

Est. Class Sessions: 2

Daily Practice and Problems

Teacher Notes
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TIMS Challenge

DPP Challenge FF can be used as a Problem of the Week.

  1. 370 quarters. I knew that 1.75 mm is the same as .175 cm and 1.35 mm is the same as .135 cm. I started by multiplying .175 × 100 = 17.5 cm, and .135 × 100 = 13.5 cm. The difference is 4 cm. I divided 14.8 ÷ 4 = 3.7 so I knew that I would need 3.7 × 100 quarters or 370 quarters and 370 dimes. I checked this by multiplying 370 quarters × .175 cm = 64.75 cm and 370 dimes × .135 cm = 49.95 cm. When I subtract, 64.75 − 49.95 = 14.8 cm difference.
    1. $92.50; I multiplied 370 × .25 = $92.50.
    2. $37.00. I multiplied 370 × .10 = $37.00.

FF. Stack Coins

A dime is 1.35 millimeters thick.                A quarter is 1.75 millimeters thick.

Romesh is stacking dimes and Keenya is stacking quarters. They have the same number of coins in their stacks.

  1. If Keenya's stack is 14.8 cm taller than Romesh's stack, how many quarters does Keenya have in her stack? Show how you solved this using your calculator.
    1. How much is Keenya's stack worth? Show how you decided.
    2. How much is Romesh's stack worth? Show how you decided.