Lesson 5

Decimal Points in Products

Let’s look at products that are decimals.

Problem 1

  1. Find the product of each number and \(\frac{1}{100}\).

    122.1

    11.8

    1350.1

    1.704

  2. What happens to the decimal point of the original number when you multiply it by \(\frac{1}{100}\)? Why do you think that is? Explain your reasoning.

Problem 2

Which expression has the same value as \((0.06) \boldcdot (0.154)\)? Select all that apply.

A:

\(6 \boldcdot \frac{1}{100} \boldcdot 154 \boldcdot \frac{1}{1,000}\)

B:

\(6 \boldsymbol  \boldcdot 154 \boldcdot \frac{1}{100,000}\)

C:

\(6 \boldcdot (0.1) \boldcdot 154 \boldcdot (0.01)\)

D:

\(6 \boldsymbol  \boldcdot 154 \boldcdot (0.00001)\)

E:

0.00924

Problem 3

Calculate the value of each expression by writing the decimal factors as fractions, then writing their product as a decimal. Show your reasoning.

  1. \((0.01)\boldcdot (0.02)\)
  2. \((0.3) \boldcdot (0.2)\)
  3. \((1.2) \boldcdot 5\)
  4. \((0.9) \boldcdot (1.1)\)
  5. \((1.5)\boldcdot 2\)

Problem 4

Write three numerical expressions that are equivalent to \((0.0004) \boldcdot (0.005)\).

Problem 5

Calculate each sum.

  1. \(33.1+ 1.95\)
  1. \(1.075 + 27.105\)
  1. \(0.401+9.28\)
(From Unit 5, Lesson 3.)

Problem 6

Calculate each difference. Show your reasoning.

  1. \(13.2 - 1.78\)
  1. \(23.11 - 0.376\)
  1. \(0.9 - 0.245\)
(From Unit 5, Lesson 4.)

Problem 7

On the grid, draw a quadrilateral that is not a rectangle that has an area of 18 square units. Show how you know the area is 18 square units.

A blank coordinate plane with 16 evenly spaced horizontal units and 12 evenly spaced vertical units.
(From Unit 1, Lesson 3.)