Question

Java Program

1Use a loop to add up the odd numbers between 100 and 200.

2Use a loop to determine if a number is prime. Recall: a number is prime if its only factors are 1 and itself.

3. Nested Loops:

}Write a nested loop that finds the largest prime number smaller than 125.

Answer 1

Question 1:
//TestCode1.java
public class TestCode1 {
    public static void main(String[] args)
    {
        int sum = 0;
        for(int i = 100;i<=200;i++){
            if(i%2==1){
                sum += i;
            }
        }
    }
}


Question 2:
import java.util.Scanner;
public class TestCode2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n;
        System.out.print("Enter a number : ");
        n = scanner.nextInt();
        boolean flag = true;
        for(int i = 2;i<n;i++){
            if(n%i == 0){
                flag = false;
            }
        }
        if (flag) {
            System.out.println("It is a prime number.");
        }
        else{
            System.out.println("It is a composite number.");
        }
    }
}


Question 3:
public class TestCode3 {
    public static void main(String[] args) {
        for(int j = 124;j>=1;j--) {
            boolean flag = true;
            int n = j;
            for (int i = 2; i < n; i++) {
                if (n % i == 0) {
                    flag = false;
                }
            }
            if(flag){
                System.out.println(n);
                break;
            }
        }

    }
}