All the solutions provided in McGraw Hill Math Grade 4 Answer Key PDF Chapter 4 Lesson 8 Multiply with Regrouping will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 4 Answer Key Chapter 4 Lesson 8 Multiply with Regrouping
Math in My World
Example 1
Zach bought 13 packages of lightbulbs. There are 4 lightbulbs in each package. How many lightbulbs are there in all?
Find 4 × 13.
1. Model 4 groups of 13.
2. Multiply the ones, and regroup.
3. Multiply the tens. Add the regrouped ten.
So, 4 × 13 = ____
Check Use the Distributive Property.
4 × 13 = (4 × 10) + (4 × 3)
= ___ + ___ = ____
Answer:
Zach bought 13 packages of lightbulbs.
There are 4 lightbulbs in each package.
So, 4 × 13 = 52.
Using the Distributive Property.
4 × 13 = (4 × 10) + (4 × 3)
52 = 40 + 12.
52 = 52.
Example 2
Will makes $6 an hour shampooing dogs at a pet shop. Last month he worked 38 hours. How much money did Will earn?
Find 38 × $6.
So, Will earned ____
Answer:
Will makes $6 an hour shampooing dogs at a pet shop.
Last month he worked 38 hours.
So, Will earned 228.
Talk Math
Explain how to find 6 × 37.
Check for Reasonableness
The product, _____, is close to the estimate, _____
Answer:
Multiply the ones.
6 x 7 one = 42 ones.
Write 2 in the ones place and 4 in tens place.
Multiply the tens.
6 x 3 tens = 18 tens
Write 8 in the tens place and 1 in hundreds place
Therefore the product is 222
So, 6 × 37 = 222.
Guided Practice
Multiply. Check for reasonableness.
Question 1.
Estimate:
____ × ____ = _____
Answer:
Multiplication of 23 with 4 then you get 92.
23 x 4 is 92.
Estimation of 92 is 90.
Question 2.
Estimate:
____ × ____ = _____
Answer:
Multiplication of 42 with 6 then you get 252.
42 x 6 = 252.
Estimation of 252 is 250.
Independent Practice
Multiply. Check for reasonableness.
Question 3.
Estimate:
Answer:
Multiplication of 33 with 5 then you get 165.
33 x 5 = 165.
Estimation of 165 is 170.
Question 4.
Estimate:
Answer:
Multiplication of $24 with 4 then you get $96.
$24 x 4 = $96.
Estimation of $96 is $100.
Question 5.
Estimate:
Answer:
Multiplication of 13 with 7 then you get 91.
13 x 7 = 91.
Estimation of 91 is 90.
Question 6.
29 × 4 = ____
Estimate:
Answer:
Multiplication of 29 with 4 then you get 116.
29 x 4 = 116.
Estimation of 116 is 120.
Question 7.
5 × 18 = ____
Estimate:
Answer:
Multiplication of 5 with 18 then you get 90.
18 x 5 = 90.
Estimation of 90 is 90.
Question 8.
7 × $36 = ____
Estimate:
Answer:
Multiplication of $36 with 7 then you get $252.
$36 x 7 = $252.
Estimation of $252 is $250.
Question 9.
6 × 52 = ____
Estimate:
Answer:
Multiplication of 6 with 52 then you get 312.
6 x 52 = 312.
Estimation of 312 is 310.
Question 10.
75 × 8 = ____
Estimate:
Answer:
Multiplication of 75 with 8 then you get 600.
75 x 8 = 600.
Estimation 75 is 80.
80 x 8 = 640.
Question 11.
4 × $83 = ____
Estimate:
Answer:
Multiplication of 4 with $83 then you get $332.
4 x $83 = $332.
Estimation of $332 is #330
Algebra Find the unknown number in each equation.
Question 12.
5 × 31 = x
x = ____
Answer:
Multiplication of 5 with 31 then you get 155.
5 x 31 = 155.
x = 155.
Therefore the unknown is 155.
Question 13.
63 × 7 = m
m = ____
Answer:
Multiplication of 63 with 7 then you get 441.
63 x 7 = 441.
m = 441.
Therefore the unknown is 441.
Question 14.
49 × 8 = w
w = ____
Answer:
Multiplication of 49 with 8 then you get 392.
49 x 8 = 392.
w = 392.
Therefore the unknown is 392.
Problem Solving
A local cave has walking tours. Adult tickets cost $18. Child tickets cost $15. Gemstone panning costs $12 per person.
Question 15.
The Diaz family has 2 adults and 3 children. How much would it cost for the family to go on a walking tour?
Answer:
Given that,
The cost of Adult ticket is $18.
The cost of child ticket is $15.
The total cost for 2 adults is $18 x 2 = $36.
The total cost for 3 Children is $15 x 3 = $45.
The cost for the family to go on a walking tour is $36 +$45 = $81.
Therefore the cost for the family to go on a walking tour is $81.
Question 16.
Mathematical PRACTICE 2 Reason Can the Diaz family pan for gemstones for $75? Explain.
Answer:
The cost of Gemstone panning costs is $12 per each person.
The number of persons that the Diaz family has 5.
So, 5 x $12 = $60.
The total cost for that the Diaz family went for gemstones is $60.
Yes the Diaz family can plan for gemstones for $75
Question 17.
Find the total cost for the Diaz family to take the walking tour and pan for gemstones.
Answer:
The cost for the family to go on a walking tour is $81.
The total cost for that the Diaz family went for gemstones is $60.
The total cost for the Diaz family to take the walking tour and pan for gemstones is $81 + $60 = $141.
HOT Problems
Question 18.
Mathematical PRACTICE 2 Use Number Sense Write two multiplication problems that have a product of 120.
Answer:
The two multiplication problems that have a product of 120 is
60 x 2 = 120.
2 x 60 = 120.
Question 19.
Mathematical PRACTICE 3 Which One Doesn’t Belong? Circle the multiplication problem that does not belong with the other three. Explain.
Answer:
12 x 8 = 96.
22 x 4 = 88.
42 x 2 = 84.
33 x 3 = 99.
In first three the ones place of multiplicand is 2. The fourth sum as 3 in the ones place.
So, The fourth one is not belong to other three.
Question 20.
? Building on the Essential Question What steps can I use to multiply by a two-digit number with regrouping?
Answer:
Multiply by a two-digit number with regrouping is
For example we have 12 x 3 is
regroup of 12 x 3 is 12 + 12 + 12 = 36.
It has 3 tens and 6 ones.
McGraw Hill My Math Grade 4 Chapter 4 Lesson 8 My Homework Answer Key
Practice
Multiply. Check for reasonableness.
Question 1.
Estimate:
Answer:
Multiplication of 77 with 3 then you get 231.
77 x 3 = 231.
Estimation of 231 is 230.
Question 2.
Estimate:
Answer:
Multiplication of $54 with 6 then you get $324.
$54 x 6 = $324.
Estimation of $324 is $320.
Question 3.
Estimate:
Answer:
Multiplication of 35 with 4 then you get 140.
35 x 4 = 140.
Estimation of 140 is 140.
Multiply. Check for reasonableness.
Question 4.
8 × $46 = ____
Estimate:
Answer:
Multiplication of 8 with $46 then you get $368.
$46 x 8 = $368.
Estimation of $368 is $370.
Question 5.
2 × 93 = ____
Estimate:
Answer:
Multiplication of 93 with 2 then you get 186.
93 x 2 = 186.
Estimation of 186 is 190.
Question 6.
7 × 68 = ____
Estimate:
Answer:
Multiplication of 7 with 68 then you get 476.
7 x 68 = 476.
Estimation of 476 is 480.
Question 7.
4 × 57 = ____
Estimate:
Answer:
Multiplication of 57 with 4 then you get 228.
57 x 4 = 228.
Estimation of 228 is 230.
Question 8.
$7 × 13 = ____
Estimate:
Answer:
Multiplication of 13 with $7 then you get $91.
13 x $7 = $91.
Estimation of $91 is $90.
Question 9.
5 × $85 = ____
Estimate:
Answer:
Multiplication of 5 with $85 then you get $425.
$85 x 5 = $425.
Estimation of $425 is $430.
Problem Solving
Question 10.
Mrs. Sands teaches 6 different classes per day at the high school. There are 36 students in each class. How many students does she teach in all?
Answer:
Given that,
Mrs. Sands teaches 6 different classes per day at the high school.
There are 36 students in each class.
So, 6 x 36 = 316.
Therefore 316 students does she teach in all.
Question 11.
Vin charges $25 rent for each booth at his flea market. If 8 people rent space, how much rent money will Vin collect?
Answer:
Given that,
Vin charges $25 rent for each booth at his flea market.
If 8 people rent space.
The money collect by Vin is $25 x 8 = $200.
Therefore Vin collects $200 rent space.
Question 12.
Mathematical PRACTICE 2 Use Number Sense Becky works 16 days each month. How many days will she work in 6 months?
Answer:
Given that,
Becky works 16 days each month.
Becky work in 6 months is 16 x 6 = 96.
Therefore Becky work 96 days in 6 months.
Test Practice
Question 13.
There are 25 gold paper clips and 75 silver paper clips in each box. How many silver paper clips are in 8 boxes?
A. 800
B. 640
C. 600
D. 200
Answer:
Given that,
There are 25 gold paper clips and 75 silver paper clips in each box.
The number of silver clips in 8 boxes is 8 x 75 = 600.
Option C is the correct answer.