ABC26GN0123 · Number System

Subject: General Aptitude · Chapter: Number System · Exam: 2006 · Marks: · Difficulty:

Which of the following is a prime number?
(a)143
(b)289
(c)117
(d)359
Answer
Answer (as printed): D
Explanation
Clearly, 143 is divisible by 11. So, 143 is not prime. 289 is divisible by 17. So, 289 is not prime. 117 is divisible by 3. So, 117 is not prime. $359<(20)^{2}$ and prime numbers less than 20 are 2, 3, 5, 7, 11, 13, 17, 19. And, 359 is not exactly divisible by any of them. Hence, 359 is a prime number.

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

Open in whiteboard · Browse this chapter in the app