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Write a C# program to check a number is prime or not?

Steilla Mitchel 315 19-Nov-2021

Write a C# program to check a number is prime or not?

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Updated on 19-Nov-2021

Steilla Mitchel

Steilla Mitchel

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I completed my post-graduation in 2013 in the engineering field. Engineering is the application of science and math to solve problems. Engineers figure out how things work and find practical uses for scientific discoveries. Scientists and inventors often get the credit for innovations that advance the human condition, but it is engineers who are instrumental in making those innovations available to the world. I love pet animals such as dogs, cats, etc.

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1 Answers

Ashutosh Kumar Verma

20-Nov-2021

Prime Number:

A prime number is a number that divided by self or 1 and no other number can divide that is called a prime number. 1 is not a prime number because there is must be divided by two number that are 1 and that number.

Ex-      2,3,5,7,11,13,17… etc.

Program:

using System;					

public class Program

{

 public static void Main()

 {

 int num,I;

 int temp=0;

 Console.WriteLine(“Enter a number to check whether prime or not);

 num=int.Parse(Console.ReadLine());

  for(i=2;i<=num/2;i++)

  {

   if(num%i==0)

   {

    temp=temp+1;

   }

  }

  if(temp==0)

  {

  Console.WriteLine('is Prime');

  }else

  {

  Console.WriteLine('not prime');

  }

 }

}

Output:

 Enter a number to check whether prime or not      7

7 is prime

Print all prime number between 1 to 100.

Program:

using System;					

public class Program

{

 public static void Main()

 {	

 int num,i,j;

  int temp=0, res;

  for(num=2;num<=100;num++)

  {

  for(i=2;i<=num/2;i++)

  {

   if(num%i==0)

   {

    temp=temp+1;

   }

  }

   if(temp==0)

      {

    Console.Write(' '+num);

   }else

   {

    temp=0;

   }			

 }		

 }

}

Output:

  2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97