All the solutions provided in McGraw Hill Math Grade 3 Answer Key PDF Chapter 8 Lesson 4 Multiply by 8 will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 3 Answer Key Chapter 8 Lesson 4 Multiply by 8
Math in My World
Example 1
There are 6 trees along a street. In each tree, there are 8 birds. How many birds are there altogether?
Find 6 × 8.
Each tree has a group of 8 birds.
One Way Draw an array.
Another way Draw a picture.
Use an X for each bird.
There are ____ birds altogether.
Check
The Commutative Property shows that 6 × 8 has the same product as 8 × 6. Since 8 × 6 = ___, then 6 × 8 = ____.
The 4s facts are helpful in remembering the 8s facts.
Answer:
Given that,
There are 6 trees along a street.
In each tree there are 8 birds.
Each tree has a group of 8 birds.
The array of 6 x 8 is
The picture is
The Commutative Property shows that 6 × 8 has the same product as 8 × 6.
Since 8 × 6 = 48, then 6 × 8 = 48.
Example 2
Pearl counted 5 honeybees on each of 8 flowers. How many honeybees are there altogether? Write a number sentence with a symbol for the unknown.
Find 5 × 8 = 
.
Decompose 8 into equal addends of 4 + 4.
So, 5 × 8 = ____
The unknown is ____
There are ___ honeybees.
Answer:
Given that,
Pearl counted 5 honeybees on each of 8 flowers.
The total number of honeybees are
So, 5 × 8 = 40.
The unknown is 40.
There are 40 honeybees.
Talk Math
There are 4 groups of 8 students and 8 groups of 8 students, how many students are there altogether? Explain.
Answer:
Given that,
4 groups of 8 students means 4 x 8 = 32.
There are 32 students in 4 groups.
8 groups of 8 students means 8 x 8 = 64.
There are 64 students in 8 groups.
The total number of students all together is 32 + 64 = 96.
Guided Practice
Complete the steps to find 7 × 8.
Question 1.
Label the array.
Answer:
Multiplication of 7 with 8 then you get 56.
Convert 8 into 4 + 4.
7 x 4 = 28.
7 x 4 = 28.
28 + 28 = 56.
Question 2.
Double a known fact.
So, 7 × 8 = ____
Answer:
Multiplication of 7 with 4 then you get 28.
The product is 28.
Double the product is 28 + 28 = 56.
So, 7 x 8 = 56.
Independent Practice
Double a known fact to find each product.
Question 3.
3 × 8 = ____
3 × ___ = ____
3 × ____ = ____
___ + ____ = ____
Answer:
Multiplication of 3 with 8 then you get 24.
3 x 8 = 24.
convert 8 into 4 + 4.
3 x 4 = 12.
3 x 4 = 12.
Therefore 12 + 12 = 24.
Question 4.
10 × 8 = ____
Answer:
Multiplication of 10 with 8 then you get 80.
10 x 8 = 80.
Convert 8 into 4 + 4.
10 x 4 = 40.
10 x 4 = 40.
Therefore 40 + 40 = 80.
Question 5.
8 × 8 = ____
Answer:
Multiplication of 8 with 8 then you get 64.
8 x 8 = 64.
Convert 8 into 4 + 4.
8 x 4 = 32.
8 x 4 = 32.
Therefore 32 + 32 = 64.
Question 6.
9 × 8 = ___
Answer:
Multiplication of 9 with 8 then you get 72.
9 x 8 = 72.
Convert 8 into 4 + 4
9 x 4 = 36.
9 x 4 = 36.
Therefore 36 + 36 = 72.
Use the Commutative Property to find each product. Write a related multiplication fact.
Question 7.
1 × 8 = ___
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 1 with 8 then you get 8.
1 x 8 = 8.
Multiplication of 8 with 1 then you get 8.
8 x 1 = 8.
Question 8.
0 × 8 = ____
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 0 with 8 then you get 0.
0 x 8 = 0.
Multiplication of 8 with 0 then you get 0.
8 x 0 = 0.
Question 9.
6 × 8 = ____
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 6 with 8 then you get 48.
6 x 8 = 48.
Multiplication of 8 with 6 then you get 48.
8 x 6 = 48.
Question 10.
7 × 8 = ___
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 7 with 8 then you get 56.
7 x 8 = 56.
Multiplication of 8 with 7 then you get 56.
8 x 7 = 56.
Question 11.
2 × 8 = ___
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 2 with 8 then you get 16.
2 x 8 = 16.
Multiplication of 8 with 2 then you get 16.
8 x 2 = 16.
Question 12.
4 × 8 = ___
Answer:
Commutative property states that if change in order of the numbers in multiplication the product does not change.
Multiplication of 4 with 8 then you get 32.
4 x 8 = 32.
Multiplication of 8 with 4 then you get 32.
8 x 4 = 32.
Algebra Find each unknown factor. Use the Commutative Property.
Question 13.
8 × 
= 64
× 8 = 64
The unknown is ____.
Answer:
Multiplication of 8 with 8 then you get 64.
8 x 8 = 64.
8 x 8 = 64.
The unknown is 8.
Question 14.
× 1 = 8
1 × = 8
The unknown is ____.
Answer:
Multiplication of 8 with 1 then you get 8.
8 x 1 = 8.
1 x 8 = 8.
The unknown is 8.
Question 15.
8 × = 72
× 8 = 72
The unknown is ____.
Answer:
Multiplication of 8 with 9 then you get 72.
8 x 9 = 72.
9 x 8 = 72.
The unknown is 9.
Multiply.
Question 16.
Answer:
Multiplication of 0 with 8 then you get 0.
0 x 8 = 0.
Question 17.
Answer:
Multiplication of 8 with 3 then you get 24.
8 x 3 = 24.
Question 18.
Answer:
Multiplication of 5 with 8 then you get 40.
5 x 8 = 40.
Question 19.
Answer:
Multiplication of 6 with 8 then you get 48.
6 x 8 = 48.
Problem Solving
Mathematical PRACTICE 1 Make a Plan Use the following information to solve Exercises 20-22.
Mrs. Miller’s class of 8 students want to have one or more classroom pets.
Question 20.
If each student brought in 3 goldfish, how many goldfish would they have in the classroom?
Answer:
Given that,
The total number of students in the class room is 8.
The total number of goldfish brought by students are 3.
So, 8 x 3 = 24.
Therefore there are 24 goldfish in the classroom.
Question 21.
If each student brought in 2 hamsters, how many hamsters would they have in the classroom?
Answer:
Given that,
The total number of students in the class room is 8.
The total number of hamsters brought by the students are 2.
So, 8 x 2 = 16.
Therefore there are 16 hamsters in the classroom.
Question 22.
A pet store charges $10 for a lizard. If each student pays $5, how many lizards would they be able to purchase?
Answer:
Given that,
The total number of students in the class room is 8.
The pet store charges for a lizard is $10.
The each student pays $5.
The 8 students collect is 8 x $5 = 40.
So, The number of lizards are 40/10 = 4.
Therefore the number of lizards purchase by students are 4.
HOT Problems
Question 23.
Mathematical PRACTICE 2 Use Number Sense The row that represents the products of 8 from the multiplication table is shown below. Describe one pattern in the products of 8. Will this pattern continue? Explain.
Answer:
One patten is multiplies of 8 having 8, 6, 4, 2, 0 in the ones place and all the products of of the 8 are even. This this patten will continue.
Question 24.
? Building on the Essential Question When would I choose to decompose a multiplication fact rather than draw a picture?
Answer:
Decompose the multiplication fact is decompose the one of the factor to double the unknown fact.
Example is
4 x 6 = 24.
Decompose 6 into 3 + 3.
4 x 3 = 12.
4 x 3 = 12.
The picture is
McGraw Hill My Math Grade 3 Chapter 8 Lesson 4 My Homework Answer Key
Practice
Double a known fact to find each product.
Question 1.
5 × 8 = ____
5 × ___ = ___
5 × ___ = ___
____ + ____ = ____
Answer:
Multiplication of 5 with 8 then you get 40.
5 x 8 = 40.
Convert 8 with 4 + 4.
5 x 4 = 20.
5 x 4 = 20.
The known fact is 20.
Double the product is 20 + 20 = 40.
Question 2.
4 × 8 = ____
4 × ___ = ___
4 × ___ = ___
____ + ____ = ____
Answer:
Multiplication of 4 with 8 then you get 32.
4 x 8 = 32.
Convert 8 into 4 + 4.
4 x 4 = 16.
4 x 4 = 16.
The known fact is 16.
Double the product is 16 + 16 = 32.
Algebra Find each unknown. Use the Commutative Property.
Question 3.
8 × 
= 40
× 8 = 40
The unknown is ___.
Answer:
Multiplication of 8 with 5 then you get 40.
8 x 5 = 40.
5 x 8 = 40.
The unknown is 5.
Question 4.
× 8 = 56
8 × = 56
The unknown is ___.
Answer:
Multiplication of 7 with 8 then you get 56.
7 x 8 = 56.
8 x 7 = 56.
The unknown is 7.
Question 5.
2 × 8 =
8 × 2 =
The unknown is ___.
Answer:
Multiplication of 2 with 8 then you get 16.
2 x 8 = 16.
Multiplication of 8 with 2 then you get 16.
8 x 2 = 16.
The unknown is 16.
Question 6.
8 × = 64
× 8 = 64
The unknown is ___.
Answer:
Multiplication of 8 with 8 then you get 64.
8 x 8 = 64.
8 x 8 = 64.
The unknown is 8.
Multiply.
Question 7.
Answer:
Multiplication of 1 with 8 then you get 8.
1 x 8 = 8.
Question 8.
Answer:
Multiplication of 8 with 9 then you get 72.
8 x 9 = 72.
Question 9.
Answer:
Multiplication of 8 with 0 then you get 0.
8 x 0 = 0.
Question 10.
Answer:
Multiplication of 3 with 8 then you get 24.
3 x 8 = 24.
Problem Solving
Mathematical PRACTICE 2 Use Symbols Write a multiplication sentence with a symbol for the unknown. Then solve.
Question 11.
There were 5 dolphins swimming around a tour boat. Each dolphin circled the boat 8 times. What is the total number of times all of the dolphins circled the boat?
Answer:
Given that,
There are 5 dolphins swimming around a tour boat.
Each dolphin circled the boat 8 times.
So, 5 x 8 = 40.
Therefore the total number of times all of the dolphins circled the boat is 40.
Question 12.
Cameron worked 8 hours at the coffee shop. He earned the same amount in tips each hour. At the end of his shift, Cameron had $32 in tips. How much money did he earn in tips each hour?
Answer:
Given that,
Cameron worked 8 hours at the coffee shop.
He earned the same amount in tips each hour.
Cameron had $32 in tips.
So, $32/8 = $4.
Therefore Cameron earn in tips for each hour is $4.
Test Practice
Question 13.
Stuart knows spiders have 8 legs. Which shows a known fact Stuart can double to find the number of legs on 7 spiders?
A. 4 × 3 = 12
B. 4 × 7 = 28
C. 4 × 8 = 32
D. 7 × 8 = 56
Answer:
Given that,
The total number of legs per each spider is 8 legs.
The total number of spiders are 7.
Therefore 8 x 7 = 56.
Option D is the correct answer.