Which one of the following numbers is not a prime number? Option 1: 241 Option 2: 337 Option 3: 391 Option 4: 571

Answer: 391. Solution: A prime number is divisible only by 1 and itself. Testing 391: 391 = 17 x 23, so it has divisors 1, 17, 23, and 391. Hence 391 is not a prime number. The other options (241, 337, 571) are all prime.

Quantitative Reasoning

Number System

Medium

Which one of the following numbers is not a prime number?

241

337

391

571

✅ Correct Option: 3

A prime number is divisible only by 1 and itself. Testing 391: $391 = 17 \times 23$ , so it has divisors 1, 17, 23, and 391. Hence 391 is not a prime number. The other options (241, 337, 571) are all prime.

2026: 21 May Shift 1

If I write down all the numbers from 1 to 100, then how many times I have written the digit 3 ?

2022: 20 Aug Shift 1

Match List I with List II:

List I	List II
A. Sum of first 5 primes	I. 15
B. Average of first 5 primes	II. 28
C. Sum of first 5 natural numbers	III. 3
D. Average of first 5 natural numbers	IV. 5.6

Choose the correct answer from the options given below:

2026: 12 May Shift 2

Which of the following lists of numbers is/are an Arithmetic Progression?

(A) 2, 8, 14, 20,........

(B) 0, 4, 8, 12,........

(D) 21, 17,15,........

Choose the correct answer from the options given below:

2022: 20 Aug Shift 1

$-224 + (-314) \times 9 = ?$

2023: 24 May Shift 3

The value of $(625)^{-3/4}$ is:

2025: 20 May Shift 2

The remainder when $(15^{23} + 23^{23})$ is divided by 19, is:

Which one of the following numbers is not a prime number?

Solution

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