5.5B Prime and Composite

Key points

 

Vocabulary
Prime (has only one factor pair, one and itself)
Composite (has more than one factor pair)
Divisible (able to be divided without a remainder)
Factor (part of a multiplication fact)

Practice Quiz
True or False. 
1. All composite numbers are even. 
(False, 9 is composite 1, 3, 9, and it is odd)

2. One is prime. 
(False, it is neither even or odd)

3. The first 5 prime numbers add up to be 28. 
(True, the sum 2, 3, 5, 7, 11 = 28)

4. The number 2 is composite 
(False, it's the ONLY even prime)

5. In the number 12,345 which number is composite? 
(4)

6. Which factor pair contains two composite numbers? (2, 6), (4, 8), (5, 7), (1, 5). 
((4,8))

7. Which factor pair contains two prime numbers? (2, 5), (4, 8), (5, 9), (1, 5). 
((2,5))

8. Is 465 prime or composite? 
(Composite. The number is divisible by 5. It ends in a 5 or 0)

9. Is 123 prime or composite? 
(Composite. The number is divisible by 3. Because 1 + 2 + 3 = 6 and 6 is divisible by 3, 123 is divisible by 3.)

10. Is 724 prime or composite? 
(Composite. The number is divisible by 2. It is even.)

11. Is 111,111,111 prime or composite? 
(Composite. The digital sum is 9 which means it can be divisible by 3 or 9.)

Flashcard Practice

Game
Find all the Factors

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