Multiply by 2-Digit Numbers
Name
2.2
?
Number and Operations—5.3.B Also 5.3.A MATHEMATICAL PROCESSES 5.1.B, 5.1.D
Multiply by 2-Digit Numbers
Essential Question
How do you multiply by 2-digit numbers?
Unlock Unlock the the Problem Problem A Siberian tiger sleeps as much as 18 hours a day, or 126 hours per week. About how many hours does a tiger sleep in a year? There are 52 weeks in one year. Use place value and regrouping. STEP 1 Estimate: 126 × 52 Think: 100 × 50 = __ STEP 2 Multiply by the ones.
12 6 × 52 __ 126 × 2 ones = __ ones
Math Talk Mathematical Processes
STEP 3 Multiply by the tens.
Are there different numbers you could have used in Step 1 to find an estimate that is closer to the actual answer? Explain.
126 × 52 __
126 × 5 tens = __ tens, or __ ones STEP 4 Add the partial products.
Remember
126 × 52 __
© Houghton Mifflin Harcourt Publishing Company
← 126 × 2 +
Use patterns of zeros to find the product of multiples of 10.
← 126 × 50
3 × 4 = 12 3 × 40 = 120
30 × 40 = 1,200
3 × 400 = 1,200
300 × 40 = 12,000
So, a Siberian tiger sleeps about __ hours in one year.
Module 2
61
Share Share and and Show Show Complete to find the product. 1.
x
6 4 4 3
+
2.
x
← 64 × _ ← 64 × _
5 7 1 3 8
+
← 571 × _ ← 571 × _
Estimate. Then find the product. 3. Estimate: __
4. Estimate: __
24 × 15 __
37 × 63 __
5. Estimate: __
384 × 45 __
Problem Problem Solving Solving Practice: Copy and Solve Estimate. Then find the product. 6. 54 × 31
7. 42 × 26
8. 38 × 64
9. 63 × 16
10. 204 × 41
11. 534 × 25
12. 722 × 39
13. 957 × 43
14. When you multiply 235 and 4 tens in 235 × 43, why does its product
15.
62
Write Math Communicate How is multiplying a number by a 2-digit number similar to multiplying the number by a 1-digit number? How is it different?
© Houghton Mifflin Harcourt Publishing Company
have a zero in the ones place? Explain.
Name
Problem Problem Solving Solving Use the table for 16–19. 16. How much sleep does a jaguar get in 1 year?
17.
Multi-Step In 1 year, how many more hours of sleep does a giant armadillo get than a platypus?
Animal Sleep Amounts Animal
Amount (usual hours per week)
Jaguar
77
Giant Armadillo
127
Owl Monkey
119
Platypus
98
Three-Toed Sloth
18.
Multi-Step Owl monkeys sleep during the day, waking about 15 minutes after sundown to find food. At midnight, they rest for an hour or two, then continue to feed until sunrise. How many hours are owl monkeys awake in 1 year?
Write Math
101
Show Your Work
19. Three-toed sloths move very slowly, using as
little energy as possible. They sleep, eat, and even give birth upside down. A baby sloth may cling to its mother for as much as 36 weeks after being born. How much of that time is the sloth asleep?
20. A tiger can eat as much as 40 pounds of food
© Houghton Mifflin Harcourt Publishing Company
at a time, but it may go for several days without eating anything. Suppose a Siberian tiger in the wild eats an average of 18 pounds of food per day. How much food will the tiger eat in 28 days if he eats that amount each day?
21. Multi-Step Tickets to a museum cost $17
each. For a field trip, the museum offers a $4 discount on each ticket. How much will tickets for 32 students cost?
Module 2 • Lesson 2
63
Mathematical Processes M Model ¥ Reason ¥ Communicate M
Daily Daily Assessment Assessment Task Task Fill in the bubble completely to show your answer. 22. In a locker, you find the ultimate puzzle book with 385 pages. There is
also a clue leading you to another locker. Multiply the number of pages by 23 to get the code for the next locker. What is the code?
A
7,755
B
6,545
C
1,925
D
8,855
23. Which estimate will help you solve this multiplication problem?
246 × 17 =
A
200 × 10
B
300 × 10
C
200 × 20
D
300 × 20
24. Multi-Step Charlie worked 45 hours this week. He earned $12 per hour.
If he spent $134 for a new bicycle, how much money does he have left?
A
$383
B
$406
C
$414
D
$674
TEXAS Test Prep though it would be unlikely for a sloth to stay in motion for more than a few moments, how far would a sloth travel in 45 minutes at that speed?
64
A
270 feet
B
60 feet
C
675 feet
D
6,750 feet
© Houghton Mifflin Harcourt Publishing Company
25. A sloth’s maximum speed on the ground is 15 feet in 1 minute. Even
Number and Operations—5.3.B Also, 5.3.A MATHEMATICAL PROCESSES 5.1.B, 5.1.D
H o mewo rk and Practice
2.2
Name
Multiply by 2-Digit Numbers
Estimate. Then find the product. 1. 34 × 12
2. 18 × 22
3. 43 × 15
4. 58 × 37
5. 328 × 15
6. 922 × 30
7. 832 × 13
8. 372 × 24
9. 823 × 17
10. 472 × 31
11. 517 × 43
12. 658 × 83
Problem Problem Solving Solving
© Houghton Mifflin Harcourt Publishing Company
13. A male lion needs as much as 15 pounds of food
each day, or 105 pounds of food each week. How much food does a lion need in one year? There are 52 weeks in one year.
14. An African elephant in the wild will eat for
as long as 16 hours each day. For how many hours does an elephant eat in one year? There are 365 days in one year.
Module 2 • Lesson 2 65
TEXAS Test Prep
Lesson Lesson Check Check Fill in the bubble completely to show your answer.
composition notebook. There is a clue on the last page of the notebook. It says to multiply the number of pages in the book that were filled by 17. This is the code for a free prize in the lunchroom. What is the code?
A
2,432
B
1,240
C
2,346
D
2,436
17. Marcus builds a brick wall that is 23 bricks
48 minutes every day for 17 days. He estimates that he rode his bike for about 400 minutes in all. Which of the following statements is true?
A
Jesse estimated correctly.
B
Jesse rode his bike for about 1,000 minutes.
C
Jesse rode his bike for about 70 minutes.
D
Jesse rode his bike for about 500 minutes.
18. The parents club buys 12 cartons of pretzels to
across and 130 bricks high. Which is the best estimate of about how many bricks Marcus will use to build the wall?
sell as refreshments at a soccer game. There are 75 bags of pretzels in one carton. How many bags of pretzels do the parents have?
A
2,000
A
860
B
4,500
B
830
C
1,000
C
900
D
3,750
D
980
19. Multi-Step Marli worked 37 hours this week.
She earned $15 per hour. She spent $62 on a birthday gift for her sister. How much money does Marli have left?
66
16. To train for a race, Jesse rode his bike for
A
$464
B
$493
C
$378
D
$511
20. Multi-Step A farmer plants a field that can fit
27 rows of pepper plants with 14 plants in each row. She can also fit 4 rows of pumpkins with 4 plants in each row. How many plants can the farmer fit in her field?
A
378
B
394
C
6,048
D
1,512
© Houghton Mifflin Harcourt Publishing Company
15. During the school year, Luis fills 138 pages of a
2.2
?
Number and Operations—5.3.B Also 5.3.A MATHEMATICAL PROCESSES 5.1.B, 5.1.D
Multiply by 2-Digit Numbers
Essential Question
How do you multiply by 2-digit numbers?
Unlock Unlock the the Problem Problem A Siberian tiger sleeps as much as 18 hours a day, or 126 hours per week. About how many hours does a tiger sleep in a year? There are 52 weeks in one year. Use place value and regrouping. STEP 1 Estimate: 126 × 52 Think: 100 × 50 = __ STEP 2 Multiply by the ones.
12 6 × 52 __ 126 × 2 ones = __ ones
Math Talk Mathematical Processes
STEP 3 Multiply by the tens.
Are there different numbers you could have used in Step 1 to find an estimate that is closer to the actual answer? Explain.
126 × 52 __
126 × 5 tens = __ tens, or __ ones STEP 4 Add the partial products.
Remember
126 × 52 __
© Houghton Mifflin Harcourt Publishing Company
← 126 × 2 +
Use patterns of zeros to find the product of multiples of 10.
← 126 × 50
3 × 4 = 12 3 × 40 = 120
30 × 40 = 1,200
3 × 400 = 1,200
300 × 40 = 12,000
So, a Siberian tiger sleeps about __ hours in one year.
Module 2
61
Share Share and and Show Show Complete to find the product. 1.
x
6 4 4 3
+
2.
x
← 64 × _ ← 64 × _
5 7 1 3 8
+
← 571 × _ ← 571 × _
Estimate. Then find the product. 3. Estimate: __
4. Estimate: __
24 × 15 __
37 × 63 __
5. Estimate: __
384 × 45 __
Problem Problem Solving Solving Practice: Copy and Solve Estimate. Then find the product. 6. 54 × 31
7. 42 × 26
8. 38 × 64
9. 63 × 16
10. 204 × 41
11. 534 × 25
12. 722 × 39
13. 957 × 43
14. When you multiply 235 and 4 tens in 235 × 43, why does its product
15.
62
Write Math Communicate How is multiplying a number by a 2-digit number similar to multiplying the number by a 1-digit number? How is it different?
© Houghton Mifflin Harcourt Publishing Company
have a zero in the ones place? Explain.
Name
Problem Problem Solving Solving Use the table for 16–19. 16. How much sleep does a jaguar get in 1 year?
17.
Multi-Step In 1 year, how many more hours of sleep does a giant armadillo get than a platypus?
Animal Sleep Amounts Animal
Amount (usual hours per week)
Jaguar
77
Giant Armadillo
127
Owl Monkey
119
Platypus
98
Three-Toed Sloth
18.
Multi-Step Owl monkeys sleep during the day, waking about 15 minutes after sundown to find food. At midnight, they rest for an hour or two, then continue to feed until sunrise. How many hours are owl monkeys awake in 1 year?
Write Math
101
Show Your Work
19. Three-toed sloths move very slowly, using as
little energy as possible. They sleep, eat, and even give birth upside down. A baby sloth may cling to its mother for as much as 36 weeks after being born. How much of that time is the sloth asleep?
20. A tiger can eat as much as 40 pounds of food
© Houghton Mifflin Harcourt Publishing Company
at a time, but it may go for several days without eating anything. Suppose a Siberian tiger in the wild eats an average of 18 pounds of food per day. How much food will the tiger eat in 28 days if he eats that amount each day?
21. Multi-Step Tickets to a museum cost $17
each. For a field trip, the museum offers a $4 discount on each ticket. How much will tickets for 32 students cost?
Module 2 • Lesson 2
63
Mathematical Processes M Model ¥ Reason ¥ Communicate M
Daily Daily Assessment Assessment Task Task Fill in the bubble completely to show your answer. 22. In a locker, you find the ultimate puzzle book with 385 pages. There is
also a clue leading you to another locker. Multiply the number of pages by 23 to get the code for the next locker. What is the code?
A
7,755
B
6,545
C
1,925
D
8,855
23. Which estimate will help you solve this multiplication problem?
246 × 17 =
A
200 × 10
B
300 × 10
C
200 × 20
D
300 × 20
24. Multi-Step Charlie worked 45 hours this week. He earned $12 per hour.
If he spent $134 for a new bicycle, how much money does he have left?
A
$383
B
$406
C
$414
D
$674
TEXAS Test Prep though it would be unlikely for a sloth to stay in motion for more than a few moments, how far would a sloth travel in 45 minutes at that speed?
64
A
270 feet
B
60 feet
C
675 feet
D
6,750 feet
© Houghton Mifflin Harcourt Publishing Company
25. A sloth’s maximum speed on the ground is 15 feet in 1 minute. Even
Number and Operations—5.3.B Also, 5.3.A MATHEMATICAL PROCESSES 5.1.B, 5.1.D
H o mewo rk and Practice
2.2
Name
Multiply by 2-Digit Numbers
Estimate. Then find the product. 1. 34 × 12
2. 18 × 22
3. 43 × 15
4. 58 × 37
5. 328 × 15
6. 922 × 30
7. 832 × 13
8. 372 × 24
9. 823 × 17
10. 472 × 31
11. 517 × 43
12. 658 × 83
Problem Problem Solving Solving
© Houghton Mifflin Harcourt Publishing Company
13. A male lion needs as much as 15 pounds of food
each day, or 105 pounds of food each week. How much food does a lion need in one year? There are 52 weeks in one year.
14. An African elephant in the wild will eat for
as long as 16 hours each day. For how many hours does an elephant eat in one year? There are 365 days in one year.
Module 2 • Lesson 2 65
TEXAS Test Prep
Lesson Lesson Check Check Fill in the bubble completely to show your answer.
composition notebook. There is a clue on the last page of the notebook. It says to multiply the number of pages in the book that were filled by 17. This is the code for a free prize in the lunchroom. What is the code?
A
2,432
B
1,240
C
2,346
D
2,436
17. Marcus builds a brick wall that is 23 bricks
48 minutes every day for 17 days. He estimates that he rode his bike for about 400 minutes in all. Which of the following statements is true?
A
Jesse estimated correctly.
B
Jesse rode his bike for about 1,000 minutes.
C
Jesse rode his bike for about 70 minutes.
D
Jesse rode his bike for about 500 minutes.
18. The parents club buys 12 cartons of pretzels to
across and 130 bricks high. Which is the best estimate of about how many bricks Marcus will use to build the wall?
sell as refreshments at a soccer game. There are 75 bags of pretzels in one carton. How many bags of pretzels do the parents have?
A
2,000
A
860
B
4,500
B
830
C
1,000
C
900
D
3,750
D
980
19. Multi-Step Marli worked 37 hours this week.
She earned $15 per hour. She spent $62 on a birthday gift for her sister. How much money does Marli have left?
66
16. To train for a race, Jesse rode his bike for
A
$464
B
$493
C
$378
D
$511
20. Multi-Step A farmer plants a field that can fit
27 rows of pepper plants with 14 plants in each row. She can also fit 4 rows of pumpkins with 4 plants in each row. How many plants can the farmer fit in her field?
A
378
B
394
C
6,048
D
1,512
© Houghton Mifflin Harcourt Publishing Company
15. During the school year, Luis fills 138 pages of a
