Section B: Practice Problems Relate Multiplication and Division

Section Summary

Details

In this section, we learned how multiplication and division are related.

$6 \times 5 = ?$

$30 \div 5 = ?$

$30 \div 6 = ?$

We used strategies to multiply and divide and worked towards fluent multiplication and division within 100.

Diagram. Rectangle split into 2 parts. One part partitioned into 3 rows of 5 of the same size squares, the other partitioned into 3 rows of 2 of the same size squares.

$7 \times 3$
$(5 \times 3) + (2 \times 3)$

Problem 1 (Lesson 6)

There are 35 books on the bookcase. There are 7 books on each shelf. How many shelves are there? Explain how the equations $35 \div 7 = ?$ and $? \times 7 = 35$ both represent the situation.

Problem 2 (Lesson 7)

There are 24 eggs in the container. There are 6 in each row. How many rows of eggs are there?

Write an equation that represents the situation. Use a symbol for the unknown. Then, answer the question.

Problem 3 (Lesson 8)

For each multiplication equation, write a related division fact you know from the multiplication equation.

$8 \times 5 = 40$
$2 \times 9 = 18$

Problem 4 (Lesson 9)

Lin knows $8 \times 5 = 40$ . Explain how she can use this fact to find $8 \times 4$ .

Problem 5 (Lesson 10)

Highlight parts of the diagram to show the expression $(5 \times 7) + (2 \times 7)$ .
Explain how you could use the diagram to calculate $7 \times 7$ .

Problem 6 (Lesson 11)

Mark or shade the rectangle to show a strategy for finding its area. Then, explain how to use the diagram to find the area.

Problem 7 (Exploration)

Noah finds $9 \times 8$ by calculating $(10 \times 8) - (1 \times 8)$ .

Make a drawing showing why Noah’s calculation works.
Use Noah’s method to calculate $9 \times 8$ .