Java Program to Determine Whether an Input Positive Integer is Prime

How can we write a Java program to determine whether an input positive integer is prime?

To write a Java program that determines whether an input positive integer is prime, we can follow the steps below. Let's walk through the explanation and code snippet provided.

Understanding Prime Numbers:

Prime numbers are positive integers that have exactly two distinct factors - 1 and the number itself. For example, 2, 3, 5, 7 are prime numbers as they can only be divided by 1 and the number itself.

Java Program to Determine Prime Number:

To determine whether an input positive integer is prime, we can use the following Java program: import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.print("Enter a positive integer: "); int num = input.nextInt(); boolean isPrime = true; if (num <= 1) { isPrime = false; } else { for (int i = 2; i <= Math.sqrt(num); i++) { if (num % i == 0) { isPrime = false; break; } } } if (isPrime) { System.out.println(num + " is prime"); } else { System.out.println(num + " is not prime"); } } }

Explanation of the Program:

- We first prompt the user to enter a positive integer using the Scanner class. - We initialize a boolean variable 'isPrime' to true, which we will use to determine whether the number is prime or not. - If the input number is less than or equal to 1, it is not prime. - We then loop through numbers from 2 to the square root of the input number. If the input number is divisible by any of these numbers, it is not prime. - If the loop completes without finding a factor, the number is prime, and we print a message indicating that the input number is prime. I hope this explanation helps in understanding how to write a Java program to determine whether an input positive integer is prime.
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