Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 17)
17.
The smallest 3 digit prime number is:
101
103
109
113
Answer: Option
Explanation:

The smallest 3-digit number is 100, which is divisible by 2.

100 is not a prime number.

101 < 11 and 101 is not divisible by any of the prime numbers 2, 3, 5, 7, 11.

101 is a prime number.

Hence 101 is the smallest 3-digit prime number.

Discussion:
22 comments Page 1 of 3.

Kusuma jayram said:   6 years ago
As we all know that the smallest three-digit number is 100 and it's square root is 10 but it is not a prime number as given in the question.

101 is the smallest one and is greater than 100 also, so we need to consider the primary numbers till 11 (11>10) and this can be applicable in all cases.
(1)

Ayushi said:   7 years ago
As 101 is not divisible by any number from 2 to 11 so for it to be a composite number it must be a product of 2 or more numbers greater than 11 which is not possible as 101<11^2< product of 2 or more numbers greater than 11.

Shubham garg said:   7 years ago
Number 101 is not a prime number because it can be divisible by 1, 3, or itself and the prime number definition says that any number which can be divisible be 1 or itself a prime number. So 101 is not a prime number.

Sharat J said:   1 decade ago
I am doing this in even simplest way.

101=1+0+1=2 //prime number.

103=1+0+3=4 //not prime number.

109=1+0+9=10 //not prime number.

113=1+1+3=5 //prime number.

But, 2 is small then 5 so the answer is 101.

Puneet said:   1 decade ago
No.
For example 97 is a prime number,
But 9+7=16 (which is a prime number).

Also 127 is a prime number, but 1+2+7=10 ain't.
Similarly 103, 107, 119, 127, 149 etc etc.

Manoj said:   9 years ago
(11)^2 > = 101.
the prime numbers less than or equal to 11 are 2, 3, 5, 7, 11.
Clearly,none of them divides 101.
So, 101 is a prime number.

Komal Gajbhiye said:   8 years ago
Except 2 and 3 every prime number can b written in the form of 2k+or-1.

Here 101 is 2*50+1.
Which means k=50.
Therefore 101 is prime number.

Shaban Mirimu said:   5 years ago
Apply digital root, 1 + 0 + 0 = 1 and 1 is not a prime number.
101---1 + 0 + 1 = 2 and 2 is a prime number. So, 101 is the answer.
(15)

Arya said:   1 decade ago
Why we using this step (square root on 101 and also < 11) I can't understand please explain me?

Achsah said:   7 years ago
Number 101 is not divisible by 3. It is a prime number. Please explain the solution clearly.


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