# 8. Which of the following numbers are prime? (a) 23     (b) 51     (c) 37      (d) 26

(a) 23,23=1 23,23=23 123,23=1 23,23=23 1 23 has only two factors, 1 and 23. Therefore, it is a prime number.

(b) 51,51=1 51,51=3 1751,51=1 51,51=3 17 51 has four factors, 1, 3, 17, 51. Therefore, it is not a prime number. It is a composite number.

(c) 37 It has only two factors, 1 and 37. Therefore, it is a prime number.

(d) 26 26 has four factors (1, 2, 13, 26). Therefore, it is not a prime number. It is a composite number.

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