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.

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.

Suparna said:   1 decade ago
Is this method can be applied in every case?

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.

Kalyan said:   1 decade ago
16 is not a prime. But in the above discussion it seems 16 as prime number.

Vikas mahant said:   1 decade ago
Prime number is divisible by 1 and itself.

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

Tareque said:   9 years ago
Please give me a list of prime numbers from 101 to 2000.

Help me to get it.

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.

Sohel said:   8 years ago
Please, anybody, provide answer correctly in details with easy formula.

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.


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