Which is not a prime number? · ABC26GN0394

Subject: General Aptitude · Chapter: Number System · Exam: Indian Railways Gr. ‘D’ Exam 2014

Which is not a prime number?

(a)13

(b)19

(c)21

(d)17

Answer

Answer (as printed): C

Explanation

$21=3 \times 7$ is not a prime number because 21 is a composite number.

Explanation as extracted from the printed page; notation may be imperfect.

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