Consider the following numbers :

1. 437

2. 797

3. 1073

How many of the above numbers are prime ? 

This question was previously asked in
CDS Elementary Mathematics 16 April 2023 Official Paper
View all CDS Papers >
  1. Only one 
  2. Only two  
  3. All three 
  4. None

Answer (Detailed Solution Below)

Option 1 : Only one 
Free
UPSC CDS 01/2025 General Knowledge Full Mock Test
7.9 K Users
120 Questions 100 Marks 120 Mins

Detailed Solution

Download Solution PDF

Concept:

Prime Number:

  • A prime number is a positive integer greater than 1 that has no positive integer divisors other than 1 and itself.
  • In other words, a prime number is only divisible by 1 and itself.
  • To determine whether a number is prime or not: Test its divisibility by all the integers from 2 to the square root of the number.
  • If none of these integers divide the number, then the number is prime.

 

Calculation:

437 = 19 × 23    

It is not a prime number 

1073 = 29 × 37 

It is not a prime number 

Check for 797:   √797 ≈ 28.2.

The prime numbers below 28 are

2, 3, 5, 7, 11, 13, 17, 19, 23

797 is not divisible by any of the given numbers 

Therefore, we can conclude that 797 is a prime number.

∴ Out of the three given numbers, only 1 i.e. 797 number is prime.

Latest CDS Updates

Last updated on May 29, 2025

-> The UPSC CDS 2 Notification has been released at upsconline.gov.in. for 453 vacancies.

-> Candidates can apply online from 28th May to 17th June 2025.

-> The CDS 2 Exam will be held on 14th September 2025.

-> Attempt UPSC CDS Free Mock Test to boost your score.

-> The selection process includes Written Examination, SSB Interview, Document Verification, and Medical Examination.  

-> Refer to the CDS Previous Year Papers to enhance your preparation. 

Get Free Access Now
Hot Links: teen patti real cash game teen patti master old version master teen patti