Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 91)
91.
Which one of the following is a prime number ?
Answer: Option
Explanation:
437 > 22
All prime numbers less than 22 are : 2, 3, 5, 7, 11, 13, 17, 19.
161 is divisible by 7, and 221 is divisible by 13.
373 is not divisible by any of the above prime numbers.
373 is prime.
Discussion:
10 comments Page 1 of 1.
Marthandan said:
1 decade ago
Could you please explain the step square-root-of(437)>22 ?
(2)
Dks said:
1 decade ago
Most prime numbers are either of the form 6k-1 or 6K+1.
(3)
Ashraful said:
1 decade ago
As square-root-of(437)is very close to 22 & there is no prime numbers between 20-22 so 437 must be divisible by greater than 22, that must be a prime numbers.
23 is divisor of 437.
23 is divisor of 437.
(2)
Shashank said:
1 decade ago
Let p be a given number and n be the smallest counting no such that n^2>p.
Now test whether p is divisible by any of the prime no. less then or equal to n. If yes p is not prime no. otherwise, it is prime.
For ex. 91.
10^>91 and prime no. below 10 are 2, 3, 5, 7 then 91 is divisible by 7.
So 91 is not prime no.
Now test whether p is divisible by any of the prime no. less then or equal to n. If yes p is not prime no. otherwise, it is prime.
For ex. 91.
10^>91 and prime no. below 10 are 2, 3, 5, 7 then 91 is divisible by 7.
So 91 is not prime no.
(5)
Aparna said:
1 decade ago
I did not get it please explain me.
(2)
Ashish said:
9 years ago
161 satisfies 6k-1 (for k = 27) but it is not a prime number why?
(2)
Radhika Deshmukh said:
6 years ago
161 also divisible by 7.
Barsha said:
4 years ago
Please explain well to get the answer.
(1)
Ali said:
3 years ago
What is the connection of square root with a prime number? please explain.
(3)
Sharumathi s said:
6 months ago
Can anyone please explain the first step?
Why is the square root used?
Why is the square root used?
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