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Coding Interview

# coding interview questions part 2

## is Prime

Prime Number is a number which can be divided evenly only by 1, or itself.
The prime number has only two divisors, 1 and same number. Prime numbers mainly used in public key cryptography.
Example:-
13 We can divide only by 1 or 13. 13 doesn’t have any other divisor. So, it is a prime number.
12 We can divide 1, 2,3,4,6. 12 has many divisors. So, it is not a prime number.

## Source Code

```package com.dsacode.Probelms;

public static void main(String[] args) {
int number = 20;

System.out.print("Print the first "+ number +" primenumbers :");

for(int i = 1; i <= number; i++){
if(oj.isPrime(i))
System.out.print(i +" ");
}
}

public boolean isPrime(int num){
for(int i=2; i < num; i++){

if(num % i == 0)
return false;

}
return true;
}

}
```
```#include "stdafx.h"

#include < iostream >
using namespace std;

bool isPrime(int num){
for (int i = 2; i < num; i++){

if (num % i == 0)
return false;

}
return true;
}

int _tmain(int argc, _TCHAR* argv[])
{
int number = 20;
cout << "Print the first " << number << " primenumbers :";
for (int i = 1; i <= number; i++){
if (isPrime(i))
cout << i << " ";
}
cout << endl;

return 0;
}

```

## Output

`Print the first 20 primenumbers :1 2 3 5 7 11 13 17 19`

1 2 3 4 5