All the solutions provided in McGraw Hill Math Grade 3 Answer Key PDF Chapter 8 Lesson 8 Multiply by 11 and 12 will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 3 Answer Key Chapter 8 Lesson 8 Multiply by 11 and 12
Math in My World
Example 1
There are 11 straws in a package. Helen bought 4 packages. How many straws does Helen have?
Find 4 × 11.
The product of 11 and a single-digit factor has two digits. Each digit in the product is the same as the factor that is not 11.
So, 4 × 11 = ____.
Another Way Use models.
Model 4 rows of 11 counters. Draw your result.
Use repeated addition.
11 + 11 + 11 + 11 = ____
The model shows 4 × 11 = ____
Helen has ____ straws.
Answer:
There are 11 straws in a package.
Helen bought 4 packages.
The product of 11 and a single-digit factor has two digits.
Each digit in the product is the same as the factor that is not 11.
So, 4 × 11 = 44.
Another Way is
The model is 4 rows of 11 counters.
Known use the repeated addition.
11 + 11 + 11 + 11 = 44
The model shows 4 × 11 = 44
Helen has 44 straws.
Example 2
There are 12 inches in one foot. How many inches are in 6 feet?
Find 6 × 12 = 
1. Decompose 12 into addends of 10 + 2. Use two different colored counters to make an array.
2. Multiply each part.
6 × 10 = ____
6 × 2 = ____
3. Then add.
60 + 12 = ____
So, 6 × 12 = ____. There are ___ inches in 6 feet.
Answer:
Given that,
There are 12 inches in one foot.
The number of inches in 6 feet’s are 6 x 12 = 72.
Decompose 12 into 10 + 2.
6 × 10 = 60.
6 × 2 = 12.
Known add 60 and 12.
60 + 12 = 72
So, 6 × 12 = 72.
There are 72 inches in 6 feet.
Talk Math
In finding 6 × 12, could you double a known fact? Explain.
Answer:
The multiplication of 6 with 12 then you get 72.
6 x 12 = 72.
Double the known fact is 6 x 12 + 6 x 12.
72 + 72 = 144.
Yes we can double the known fact.
Guided Practice
Question 1.
Write an addition sentence and a multiplication sentence for the number of counters in 7 rows of 11 counters.
11 + ____ + ____ + ____ + _____
_____ + ____ = _____
_____ × 11 = _____
Answer:
The multiplication sentence is 7 x 1 = 77.
Multiplication of 7 with 11 then you get 77.
The addition sentence is
11 + 11 + 11 + 11 + 11 + 11 + 11 = 77.
Independent Practice
Write an addition sentence and a multiplication sentence for each.
Question 2.
6 rows of 11 counters ____ + ___ + ____ + ____ + ____ + ____ = ____
_____ × ____ = _____
Answer:
The multiplication sentence of 6 rows and 11 counters is
6 x 11 = 66.
Multiplication of 6 with 11 then you get 66.
The addition sentence is
11 + 11 + 11 + 11 + 11 + 11 = 66
Question 3.
4 rows of 12 counters ___ + ___ + ____ + ____ = ____
_____ × ____ = _____
Answer:
The multiplication sentence of 4 rows of 12 counters is
4 x 12 = 48.
Multiplication of 4 with 12 then you get 48.
The addition sentence is 12 + 12 + 12 + 12 = 48.
Question 4.
3 rows of 11 counters ___ + ____ + ___ = ____
_____ × ____ = _____
Answer:
The multiplication sentence of 3 rows of 11 counters is
3 x 11 = 33.
Multiplication of 3 with 11 then you get 33.
The addition sentence is 11 + 11 + 11 = 33.
Question 5.
3 rows of 12 counters ___ + ____ + ____ = _____
_____ × ____ = _____
Answer:
The multiplication sentence of 3 rows of 12 is
3 x 12 = 36.
Multiplication of 3 with 12 then you get 36.
The addition sentence is 12 + 12 + 12 = 36.
Draw a line to match each fact to its decomposed parts. Then find each product.
Answer:
Problem Solving
Question 11.
How many holes are in 12 pretzels like the one shown? Write a multiplication sentence to solve.
Answer:
Given that,
The holes in the shown pretzels is 12.
The number of holes in the 12 pretzels is
So, 12 x 12 = 144.
The multiplication sentence is 12 x 12 = 144.
Therefore are 144 holes in the pretzels.
Question 12.
Today is Bethany’s eighth birthday. How many months old is she? Write a multiplication sentence to solve.
Answer:
Given that,
Today is Bethany’s eighth birthday.
The number of months she old is
1 year equal to 12 months.
The multiplication sentence is
12 x 8 = 96.
Therefore she is 96 months old.
Question 13.
Math books are stacked in piles of 11 books. There are 6 piles. Are there enough books for two classes that have 35 students each? Explain.
Answer:
Given that,
Math books are stacked in piles of 11 books.
There are 6 piles.
The number of books are 11 x 6 = 66.
The number of students in each class is 35.
In two classes is 35 x 2 = 70.
There are 70 students and 66 books.
Therefore there are no enough books to the students.
HOT Problems
Question 14.
Mathematical PRACTICE 2 Use Number Sense Maren forgot some of her 12s facts. She wants to find 6 × 12, but all she can remember is 5 × 12 = 60. How could she use the fact 5 × 12 = 60 to find 6 × 12? Explain.
Answer:
Given that,
Maren forgot some of her 12s facts.
She wants to find 6 × 12, but all she can remember is 5 × 12 = 60.
Know add to the product of 5 x 12.
That is 60 + 12 = 72.
72 is the product of 6 x 12.
Question 15.
Mathematical PRACTICE 5 Use Mental Math Double a known fact to find 12 × 11. Explain the method you used.
Answer:
Given that is 12 x 11.
12 x 11 = 132.
Decompose the 12 into 6 + 6.
Know 6 x 11 + 6 x 11 = 12 x 11.
Therefore Double the fact to find the 12 x 11 is 6 x 11.
Question 16.
? Building on the Essential Question How can I use multiplication facts with smaller numbers to remember multiplication facts with 11 and 12?
Answer:
The multiplication facts with 11 and 12 are very simple to remember.
11 x 1 = 11.
11 x 2 = 22.
To continue the table add 11 to the product.
For 12 facts also.
12 x 1 = 12.
12 x 2 = 24.
The continue the table add 12 to the product.
McGraw Hill My Math Grade 3 Chapter 8 Lesson 8 My Homework Answer Key
Practice
Write an addition sentence and a multiplication sentence for each.
Question 1.
5 rows of 11 counters ___ + ___ + ___ + ____ + ____ = ____
____ × ____ = ____
Answer:
The multiplication sentence of 5 rows of 11 counters is
5 x 11 = 55.
Multiplication of 5 with 11 then you get 55.
The addition sentence is 11 + 11 + 11 + 11 + 11 = 55.
Question 2.
3 rows of 12 counters ___ + ____ + ____ = ____
____ × ____ = ____
Answer:
The multiplication of 3 rows of 12 counters is
3 x 12 = 36.
Multiplication of 3 with 12 then you get 36.
The addition sentence is 12 + 12 + 12 = 36.
Use repeated addition to find each product.
Question 3.
3 × 11 = ____
Answer:
Multiplication of 3 with 11 then you get 33.
3 x 11 = 33.
The addition sentence is 11 + 11 + 11 = 33.
Question 4.
8 × 12 = ____
Answer:
Multiplication of 8 with 12 then you 96.
8 x 12 = 96.
The addition sentence is 12 + 12 + 12 + 12 + 12 + 12 + 12 + 12 = 96.
Decompose one factor to find each product.
Question 5.
5 × 12 = ____
Answer:
Multiplication of 5 with 12 equal to 60.
5 x 12 = 60.
Decompose 12 with 6 + 6.
5 x 6 = 30.
5 x 6 = 30.
Add 30 + 30 = 60.
Therefore the product is 60.
Question 6.
7 × 11 = ____
Answer:
Multiplication of 7 with 11 then you get 77.
Decompose 11 with 10 + 1.
7 x 10 = 70.
7 x 1 = 7.
Add 70 + 7 = 77.
Therefore the product is 77.
Problem Solving
Question 7.
How many eggs are there altogether in 7 dozen eggs? (Hint: 1 dozen = 12)
Answer:
We know that 1 dozen = 12 eggs.
The number of eggs in 7 dozens is 7 x 12 = 84.
Question 8.
How many months are in 6 years?
Answer:
We know that,
1 year = 12 months.
The number of months in 6 years is 6 x 12 = 72.
Question 9.
A certain butterfly has 9 spots. How many spots would 11 of these butterflies have?
Answer:
Given that,
A certain butterfly has 9 spots..
The number of spots on 11 butterflies is 9 x 11 = 99.
Question 10.
Mathematical PRACTICE 1 Keep Trying Luke can run a mile in 7 minutes. Colleen can run a mile in 5 minutes. At this rate, how much longer would it take Luke to run 11 miles than it would take Colleen to run 11 miles?
Answer:
Given that,
Luke can run a mile in 7 minutes.
Colleen can run a mile in 5 minutes.
Luke take to run 11 miles is 7 x 11 = 77.
Colleen make to run 11 miles is 5 x 11 = 55.
So, 77 – 55 = 22 miles.
Therefore Luke run 22 miles longer than Collen.
Test Practice
Question 11.
Which number sentence does not belong with the other three?
A. 4 × 12 = 48
B. 12 × 4 = 48
C. 4 + 12 = 16
D. 12 + 12 + 12 + 12 = 48
Answer:
The number sentence does not belong with the other three is 4 + 12 = 16.
Option C is the correct answer.