Section C: Practice Problems Multiplying Larger Numbers

Section Summary

Details

In this section, we learned how to multiply single-digit numbers by multiples of ten. We used strategies to multiply teen numbers and numbers greater than 20.

$4 \times 30$

Base ten blocks. 7 sets of 1 ten and 3 ones.

$7 \times 13$

Diagram. Gridded rectangle partitioned into 3 parts, two labeled 30 with a measurement of 10 at the top, and one labeled 24 with a measurement of 8 at the top. Side measurement 3.

Area diagram. Rectangle divided into 2 parts. One part labeled 60 with a top measurement of 20, the other labeled 24, with a top measurement of 8. Left side measurement 3.

$3 \times 28$

Problem 1 (Lesson 12)

How many tens are there in 50?
How many tens are there in $7 \times 50$ ? Explain your reasoning.
What is the value of $7 \times 50$ ? Explain your reasoning.

Problem 2 (Lesson 13)

There are 4 lunch tables. There are 12 students at each table. How many students are there at the tables? Show your thinking using objects, a drawing, or a diagram.

Problem 3 (Lesson 14)

What do the 60 and 24 in the diagram represent?
Explain how to use the diagram to calculate $14 \times 6$ .

Problem 4 (Lesson 15)

There were 14 days of school in the month. There were 7 hours of school each day. How many hours of school were there during the month?

Problem 5 (Lesson 16)

Find the value of each expression. Explain or show your reasoning.

$2 \times 47$
$3 \times 25$

Problem 6 (Lesson 17)

A rope is 640 inches long. Andre cuts off 5 pieces of rope that are 16 inches each. How much rope is left?

Problem 7 (Exploration)

Here is Mai’s strategy for calculating $4 \times 21$ : “First I double 21 and that’s 42. Then I double 42 and that’s 84.”

Explain why Mai’s strategy works.
Use Mai’s strategy to find $4 \times 23$ .

Problem 8 (Exploration)

Make a list of the numbers less than 20 that do not appear in the multiplication table.
What do these numbers have in common?
Choose one of these numbers and count out that number of objects. Can you make an array out of the objects?

Problem 9 (Exploration)

Look at the two different diagrams of the same multiplication expression:

Area diagram. Rectangle divided into 2 parts. One part labeled 60 with a top measurement of 10, the other labeled 18, with a top measurement of 3. Left side measurement 6.

What multiplication expression do the two diagrams represent?
Can you show a third way to represent the same multiplication expression?
What is the value of the expression?
Write a story problem to match the expression.