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Practice each question, then open the answer or worked solution.
Write five pairs of prime numbers less than 20 whose sum is divisible by 5. (Hint: 3 + 7 = 10)
The five pairs of prime numbers less than 20 whose sum is divisible by 5 are
2 + 3 = 5
2 + 13 = 15
3 + 17 = 20
7 + 13 = 20
19 + 11 = 30
Fill in the blanks:
(a) A number with only two factors is called a ______.
(b) A number with more than two factors is called a ______.
(c) 1 is neither ______ nor ______.
(d) The smallest prime number is ______.
(e) The smallest composite number is _____.
(f) The smallest even number is ______.
(a) A number with only two factors is called a prime number.
(b) A number with more than two factors is called a composite number.
(c) 1 is neither a prime number nor a composite number.
(d) The smallest prime number is 2
(e) The smallest composite number is 4
(f) The smallest even number is 2.