# Number Sense & Numeration: Prime And Composite Numbers Answers - Grade 6 Page 2

5. For each composite number below, construct a factor tree to find the prime factors. Write
the prime factors in the blank provided. The first one has been done for you.
a.
c.
2, 3 and 5
2 and 3
Prime factors:
Prime factors:
b.
d.
3 and 7
2, 3 and 11
Prime factors:
Prime factors:
6. Circle each prime number below.
89
51
99
33
27
15
47
2
94
43
38
7
70
53
61
8
87
75
83
69
100
101
102
103
104
105
106
107
108
109
A two-digit number is prime. When you reverse the digits, the new number is also prime.
7.
There are nine numbers like this. List as many possibilities as you can. (Note: When you
reverse the digits of 18, you get 81.)
Possible answers are 11, 13, 17, 31, 37, 71, 73, 79 or 97.
TRY THIS!
Can two prime numbers other than 2 and 5 ever have a
difference of 3? Explain why or why not.
No. Any two numbers that have a difference of 3 will
have one even number among them. 2 is the only even
prime number, so no other pair exists.
Expectation: Identify and explain the relationship between composite numbers and prime numbers