All the solutions provided in McGraw Hill My Math Grade 3 Answer Key PDF Chapter 7 Lesson 4 Multiply by 4 will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 3 Answer Key Chapter 7 Lesson 4 Multiply by 4
Math in My World
Example 1
A box is packed with 4 rows of oranges. Each row has 9 oranges. How many oranges are in the box?
Find 4 × 9.
Decompose 4 into equal addends of 2 + 2.
Use the known fad of 2 × 9 and double it.
The array shows that 2 × 9 plus ____________ × 9 equals __________ × 9.
So, 4 × 9 = _____________. There are ______________ oranges in the box.
Answer:
Given that,
A box is packed with 4 rows of oranges.
Each row has 9 oranges.
The array shows that 2 × 9 plus 2 × 9 equals 4 × 9.
So, 4 × 9 = 36.
There are 36 oranges in the box.
Example 2
There are 3 bunches of bananas. Each bunch has 4 bananas. How many bananas are there altogether? Write a multiplication sentence with a symbol for the unknown. Then solve.
Solve by decomposing the factor 4 into two equal addends of 2.
Use the known fact 3 × 2 plus 3 × 2 to find the unknown.
So, 3 × 4 = ______________. The unknown is ______________.
There are ______________ bananas altogether.
Answer:
Given that,
There are 3 bunches of bananas.
Each bunch has 4 bananas.
So, 3 × 4 = 12.
The unknown is 12.
There are 12 bananas altogether.
Talk Math
Explain how knowing 2 × 7 can help you find 4 × 7.
Answer:
Given that,
2 x 7
Multiplication of 2 x 7 is 14.
2 x 7 = 14.
Product is the 14.
Double the product is 14 + 14 = 28.
Add 2x 7 + 2 x 7 then you get 4 x 7.
4 x 7 = 28.
Therefore 2 x 7 is helped to find the 4 x 7.
Guided Practice
Question 1.
Double a known fact to find 6 × 4. Label the array and complete the number sentences.
12 + 12 = ______________.
So, 6 × 4 = _______________.
Answer:
12 is the product.
Double the product is 12 + 12 = 24.
So. 6 x 4 = 24.
Independent Practice
Double a known fact to find each product. Draw and label an array.
Question 2.
8 × 4 = ______________
Answer:
Multiplication of 8 with 4 then you get 32.
8 x 4 = 32.
32 is the product.
Double the product is 32 + 32 = 64.
Know 8 x 4 + 8 x 4 = 16 x 4.
so, 16 x 4 = 64.
The array is
Question 3.
5 × 4 = _______________
Answer:
Multiplication of 5 with 4 then you get 20.
5 x 4 = 20.
20 is the product.
Double the product is 20 + 20 = 40.
Know add 5 x 4 + 5 x 4 = 10 x 4
So, 10 x 4 = 40.
The array is
Question 4.
4 × 6 = _______________
Answer:
Multiplication of 4 with 6 then 24.
4 x 6 = 24.
24 is the product.
Know double the product.
24 + 24 = 48.
Add 4 x 6 + 4 x 6 = 8 x 6
So, 8 x 6 = 48.
The array is
Question 5.
7 × 4 = ________________
Answer:
Multiplication of 7 with 4 then you get 28.
7 x 4 = 28.
28 is the product.
Know double the product.
28 + 28 = 56
Add 7 x 4 + 7 x 4 = 14 x 4
So, 14 x 4 = 56.
The array is
Algebra Find each unknown. Double a known fact.
Question 6.
7 × 4 = 
The unknown is _______________.
Answer:
Multiplication of 7 with 4 then you get 28.
28 is the product.
The unknown is 28.
Double the unknown is 28 + 28 = 56.
Question 7.
9 × 4 =
The unknown is ________________.
Answer:
Multiplication of 9 with 4 then you get 36.
9 x 4 = 36.
36 is the product.
The unknown is 36.
Double the unknown is 36 + 36 = 72.
Question 8.
The unknown is ________________.
Answer:
16 is the product.
The unknown is 16.
Double the product is 16 + 16 = 32
Question 9.
The unknown is ________________.
Answer:
The product is 40.
The unknown is 40.
Double the product is 40 + 40 = 80.
Problem Solving
Question 10.
The library offers 4 activities on Saturday. Each activity table has room for 10 children. How many children can take part in the activities? Write a multiplication sentence to solve.
Answer:
The library offers 4 activities on Saturday.
Each activity table has room for 10 children.
The multiplication sentence is 4 x 10 = 40.
Therefore the children can take part in the activities are 40.
Question 11.
Mathematical PRACTICE Reason Mitch bought 4 bottles of suntan lotion for $6 each. Later the lotion went on sale for $4 each. How many more bottles could he have bought for the same amount of money if he waited for the sale?
Answer:
Given that,
Mitch bought 4 bottles of suntan lotion for $6 each.
The cost of 4 bottles is $6 x 4 = $24.
Later the lotion went on sale for $4 each.
Known the cost of 4 bottles is $4 x 4 = $16.
So, $24 – $16 = $8.
For $8 we get 2 bottles.
Therefore he can buy 2 many more bottles if he waited for the sale.
HOT Problems
Question 12.
Mathematical PRACTICE Use Number Sense Look at the multiplication table. Circle the two numbers that represent the product of 4 and 10. Write this product as a sum of two equal addends.
Can the product of 4 and any number always be written as a sum of two equal addends? Explain.
Answer:
The product of 4 and 10 is 40.
4 x 10 = 40.
Sum of two equal addends is 20 + 20 = 40.
Yes, the product of 4 and any number always be written as a sum of two equal addends.
It is 2 x 6 = 12.
Equal addends is 6 + 6 = 12.
Question 13.
Building on the Essential Question What is one strategy I could use to multiply by 4?
Answer:
We know that 2 x 2 = 4.
To multiply a number 4 we can multiply two twice.
Is 2 x 2 + 2 x 2 = 4 x 2.
McGraw Hill My Math Grade 3 Chapter 7 Lesson 4 My Homework Answer Key
Practice
Double a known fact to find the product. Label the array and complete the number sentences.
Question 1.
4 × 5
__________ + ____________ = ___________
So, 4 × 5 = _____________.
Answer:
The product is 10.
Double the product is 10 + 10 = 20.
So, 4 x 5 = 20.
Question 2.
3 × 4
__________ + ____________ = ___________
So, 3 × 4 = _____________.
Answer:
6 is the product.
Know add the product 6 + 6 = 12.
So, 3 x 4 = 12.
Double a known fact to find each product. Draw and label an array.
Question 3.
6 × 4 = ______________
Answer:
Multiplication of 6 with 4 then you get 24.
6 x 4 = 24.
6x 4 + 6 x 4 = 12 x 4.
The product is 24.
Double the product is 24 + 24 = 48.
The array is
Question 4.
4 × 8 = ______________
Answer:
Multiplication of 4 with 8 then you get 32.
4 x 8 = 32.
4 x 8 + 4 x 8 = 8 x 8
The product is 32.
Double the product is 32 + 32 = 46.
The array is
Algebra Find each unknown. Double a known fact.
Question 5.
9 × 4 = 
The unknown is _______________.
Answer:
Multiplication of 9 with 4 then you get 36.
9 x 4 = 36.
The product is 36.
The unknown is 36
Double the unknown is 36 + 36 = 72.
Question 6.
4 × 4 =
The unknown is _______________.
Answer:
Multiplication of 4 with 4 then you get 16.
4 x 4 = 16.
The product is 16.
The unknown is 16.
Double the unknown is 16 + 16 = 32.
Problem Solving
Question 7.
Mathematical PRACTICE Model Math Melissa owns 4 sets of jewelry. Each set contains 2 earrings, 1 necklace, 1 bracelet, and 1 ring. How many pieces of jewelry does Melissa have altogether? Write a multiplication sentence.
Answer:
Given that,
Melissa owns 4 sets of jewelry.
Each set contains 2 earrings, 1 necklace, 1 bracelet, and 1 ring.
The number of pieces in each set is 5.
So, the multiplication sentence is 4 x 5 = 20.
Therefore the number of pieces of jewelry does Melissa have altogether is 20.
Vocabulary Check
Write a definition for the vocabulary word(s).
Question 8.
known fact ___________________
Answer:
A fact that you have memorized is a known fact.
Question 9.
decompose ___________________
Answer:
Decompose means break down numbers into parts.
Test Practice
Question 10.
There are 7 birdfeeders at the park. Each birdfeeder has 4 perches. How many birds can use the birdfeeders at the same time?
(A) 32 birds
(B) 28 birds
(C) 11 birds
(D) 3 birds
Answer:
Given that,
There are 7 birdfeeders at the park.
Each birdfeeder has 4 perches.
Birds can use the birdfeeders at the same time is 7 x 4 = 28.
Option B is the correct answer.