Topic A - Multiples of 10
What is 2 x 90?
180
Fill in the blanks to find 4 x 28
= 4 x (_____ + 8)
= (4 x______ ) + (4 x 8)
= _____ + ______
= ________
= 4 x (20+ 8)
= (4 x20 ) + (4 x 8)
= 80 + 32
= 112
Divide: 52 ÷ 4
Use a place value chart OR break apart 52 into 2 smaller numbers that are divisible by 4.
=52 ÷ 4
=( 40 + 12) ÷ 4
=( 40 ÷ 4) + ( 12 ÷ 4)
=10 + 3
=13
Which statement is true about the number 16?
A. 16 is a composite number because all even numbers are composite.
B. 16 is a prime number because it only has 2 factors.
C. 16 is a composite number because it has more than 2 factors.
D. 16 is a prime number because it is odd.
Answer: C.
Composite numbers have more than 2 factors!
Note: NOT ALL EVEN NUMBERS ARE COMPOSITE. (Ex: the number 2 is even, but it is prime!)
Which expressions are equal to 200? Choose three answers.
A. 20 x 10
B. 2 x 10 x 10
C. 20 x 20
D. 40 x 5
E. 40 x 50
A. 20 x 10 = 200
B. 2 x 10 x 10 = 200
D. 40 x 5 = 200
Incorrect:
C. 20 x 20= 400
E. 40 x50 = 2,000
A restaurant sells 43 hot dogs. It sells 3 times as many burgers as hot dogs. How many hotdogs does the restaurant sell? Write an equation, using the variable, h, draw a tape diagram and show your work
3 x 43= m
*Break 43 into tens and ones! You can use an area model.
= (40 x 3) + (3 x 3)
= 120 + 9
= 129 hotdogs
Divide: 63 ÷ 3
Use a place value chart OR break apart 52 into 2 smaller numbers that are divisible by 4.
=63 ÷ 3
=( 60 + 3) ÷ 3
=( 60 ÷ 3) + ( 3 ÷ 3)
=20 + 1
=21
The width of a rectangle is 4 inches. The length is 5 times as long as the width. What is the perimeter of the rectangle?
Width is 4 inches
Length is 4 x 5 = 20 inches
P = L+W+L+W
P= 20 + 4 + 20 +4
P= 24 +24
P= 48 inches
Divide: 250 ÷ 5
50
Sample solution:
Think: 5 X ____ = 250
I know 5 x 5= 25
So, 5 x 50 = 250
Multiply 64 x 3
Break 64 into tens and ones!
(60 x 3) + (4 x 3)
=180 + 12
=192
Divide: 252 ÷6
Use a place value chart OR break apart 52 into 2 smaller numbers that are divisible by 4.
=252 ÷ 6
=( 240 + 12) ÷ 6
=( 240 ÷ 6) + ( 12 ÷ 6)
=40 + 2
=42
Which numbers are factors of 18? Choose all that apply.
A. 3
B. 4
C. 9
D. 18
E. 36
F. 81
Answers: A,C,D
Note: Build a factor rainbow!
1 x 18 = 18
2 x 9 = 18
3 x 6 = 18
Robin draws a rectangle that has a width of 4 cm and a length of 60 cm. What is the area of Robin’s rectangle?
A = 60 x 4
A= 240 squared cm
Jane solved 98 x 5 by using the strategy below. Do you agree with her strategy and answer? Explain, why or why not.
= 5 x 98
= 5 x (90 + 80)
= (5 x 90) + (5 x 80)
= 450 + 400
= 850
I disagree with Jane's strategy. She did not decompose 98 correctly. There are 8 ones, not 8 tens. If she decomposed by tens and ones, her equations should look like this:
=5 x (90 + 8)
= (5 x 90) + ( 5 x 8)
= 450 + 40
=490
Which expression can be used to find 98 ÷ 7?
A. (49 ÷ 7) + (2 ÷ 7)
B. (63 ÷ 7) × (35 ÷ 7)
C. (70 ÷ 7) + (28 ÷ 7)
D. (98 ÷ 5) + (98 ÷ 2)
The answer is C.
-It is not A, because 49 + 2 Doesn't equal 98
- It is not B, because 63 x 35 doesn't equal 98
- It is not C, because 98 + 98 does not equal 98
Which number is a multiple of 8?
A. 4
B. 18
C. 32
D. 84
Answer: C
Skip count by 8!
8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88
A rectangular swimming pool has an area of 160 square meters. The width of the pool is 8 meters. What is the length of the pool?
A = L x W
160 = L x 8
160 ÷ 8 = 20
(Think 8 x ___ =160)
Luke rode his bike for 3 miles. Lior rode 14 times as many miles as Luke. How many miles did Lior bike?
Write an equation, using the variable, m. Draw a tape diagram and show your work.
3 x 14 = m
= (3 x 10) + (3 x 4)
= 30 + 12
= 42 miles
Tom has 54 baseball cards. He has 9 times as many cards as Bob.
How many cards does Bob have?
Write an equation, using variable, c.
Note: Tom has more cards. Bob cannot have a higher number than Tom.
54= 9 x c
B= 6
Tracy uses the rule, add 4, to a pattern below.
A. Finish the pattern
4, _____, _______, ________, ________
B. Is the 8th number going to be even or odd? How do you know?
A. Finish the pattern
4, 8,12,16,20
B. The 8th number will be 32. I know because 4 x 8 = 32. 32 is an even number because it ends in a 2.