Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 1)
Which one of the following is not a prime number?
Answer: Option
91 is divisible by 7. So, it is not a prime number.
104 comments Page 1 of 11.

Keshav said:   2 months ago
How to find the prime number?

Amare muluken said:   11 months ago
Thanks all for explaining the answer.

Kakrla mallikarjuna rao said:   11 months ago
I think B is the correct answer.

Vishala said:   1 year ago
Thank you all for explaining the answer.

Nishu said:   2 years ago

Thank You so much, it was very helpful to me.

Jaanu Jaanu said:   2 years ago
Thanks both of you for the clear explanations. @Hafiz and@ Dilip.

Monisha Mohanan said:   3 years ago

Prime number means that a number that is divisible only by itself and 1

Examples : 2,3,5,7,11.
Now in our question the options s 31, 61,71 and 91 here I think in our example we can find that the prime numbers only start with 2,1,3,5,7.
Thus the answer becomes 91.

Jitu said:   3 years ago
Why only 91 is not a prime number?

In this case, 71 is also divisible by 3.

Sharma said:   3 years ago
91 prime or not.

Which square number is exceeds 91?

10 ^2 right. So let's take a prime number which is less than 10.
2, 3, 5, 7.

Check the given number is divisible by 2, 3, 5, 7.
If it is divisible then it is not a prime number.
If not that would be a prime number.

Sindhuja B said:   3 years ago
The Question is "which is not a prime number".

In a very simple way how do we check whether a number is prime or not, .

The number should be divisible by one & the number it self right!.
Now see their options, that are, .

31. - is a prime number which can only be divided 1 & the number itself.
61. - same here.
71. - here too.
91. - is divisible by 1, 7, 91.

So, among other options, 91 is not a prime number.

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