Unit 5 Section C

Grids and Models

100

Find the value of 0.3 x 0.5

0.15 

200

Explain why a hundreds grid is a helpful tool for multiplying decimals like 0.3 and 0.5

Answers may vary:

A 10×10 grid has 100 squares total. Each row and column represents 0.1 (one tenth). When you shade the rows and columns, the overlapping region shows the product visually. The number of shaded squares tells you how many hundredths are in the answer.

300

Use a grid to find 0.4 × 0.7

Answer: 0.28

Strategies

100

Andre multiplies 0.28 × 37 by first finding 28 × 37, then multiplying by ___.

Fill in the blank.

Answer: 0.01

Andre's strategy: 28×37=1,036, then 1,036×0.01=10.36

This works because 0.28 is 28 hundredths (28×0.01).

200

Use Andre's strategy to find 0.15 × 24

Answer: 3.6

Step 1: 15×24=360

Step 2: 360×0.01=3.6

300

Why does multiplying by 0.01 give us the decimal product?

Answers may vary

Computation

100

Find: 2.1×7.3

15.33

200

Find: 0.6×0.8

 0.48

300

Find: 3.25 × 2.4

7.8