Question

A prime number is an integer greater than 1 that is evenly divisible by only 1 and itself. For example, 2, 3, 5, and 7 are prime numbers, but 4, 6, 8, and 9 are not. Create a PrimeNumber application that prompts the user for a number and then displays a message indicating whether the number is prime or not. Hint: The % operator can be used to determine if one number is evenly divisible by another.

b) Modify the application to prompt the user for two numbers and then display the prime numbers between those numbers.

( Java programming )

Answer 1

a)Java code:

import java.util.Scanner;
public class Main{
   public static void main(String[] args){
   Scanner input=new Scanner(System.in);
   //asking for a number
   System.out.print("Enter a number: ");
   //accepting it
   int num=input.nextInt();
   //initializing flag as 0
   int flag=0;
   //looping from 2 to number
   for(int i=2;i<num;i++)
   //checking if the number is divisible by any other number
   if(num%i==0){
   //ssetting flag as 1
   flag=1;
   //printing Not prime
   System.out.println("Not prime");
   //exiting out of loop
   break;
   }
   //checking if flag is 0
   if(flag==0)
   //printing Prime
   System.out.println("Prime");
   }
}

Screenshot:

Input and Output:

b)Java code:

import java.util.Scanner;
public class Main{
   public static void main(String[] args){
   Scanner input=new Scanner(System.in);
   //asking for a number
   System.out.print("Enter two numbers: ");
   //accepting first number
   int num1=input.nextInt();
   //accepting second number
   int num2=input.nextInt();
   //initializing flag as 0
   int flag;
   //looping from num1 to num2
   for(int num=num1;num<=num2;num++){
   //setting flag as 0
   flag=0;
   //looping from 2 to number
   for(int i=2;i<num;i++)
   //checking if the number is divisible by any other number
   if(num%i==0){
   //setting flag as 1
   flag=1;
   //breaking out of loop
   break;
   }
   //checking if flag is 0
   if(flag==0)
   //printing Prime number
   System.out.println(num);
   }
   }
}

Screenshot:

Input and Output: