1. Create a program that maps input numbers 1-7 to corresponding days of the week.

package com.examples.core;<br><br>import java.util.Scanner;<br><br>public class DayMapper {<br>    public static void main(String[] args) {<br>        Scanner scanner = new Scanner(System.in);<br>        System.out.println("Enter a number between 1 and 7:");<br>        int dayNumber = scanner.nextInt();<br>        <br>        String[] daysOfWeek = {<br>            "", // Index 0 is unused<br>            "Monday",<br>            "Tuesday",<br>            "Wednesday",<br>            "Thursday",<br>            "Friday",<br>            "Saturday",<br>            "Sunday"<br>        };<br>        <br>        if (dayNumber >= 1 && dayNumber <= 7) {<br>            System.out.println(daysOfWeek[dayNumber]);<br>        } else {<br>            System.out.println("Invalid input! Please enter a number between 1 and 7.");<br>        }<br>        <br>        scanner.close();<br>    }<br>}

2. Develop a program that takes a student's score as input and returns the corresponding grade based on predefined ranges.

package com.examples.core;<br><br>public class GradeCalculator {<br>    public static void main(String[] args) {<br>        int score = 76; // Example input<br>        String grade = calculateGrade(score);<br>        System.out.println("The student's grade is: " + grade);<br>    }<br>    <br>    public static String calculateGrade(int score) {<br>        if (score < 0 || score > 100) {<br>            return "Invalid score! Please enter a value between 0 and 100.";<br>        }<br>        <br>        if (score >= 90) return "Excellent";<br>        if (score >= 80) return "Good";<br>        if (score >= 70) return "Average";<br>        if (score >= 60) return "Pass";<br>        return "Fail";<br>    }<br>}

3. Write a program to find and print all three-digit narcissistic numbers (Armstrong numbers).

package com.examples.core;<br><br>public class NarcissisticNumbers {<br>    public static void main(String[] args) {<br>        System.out.println("Three-digit narcissistic numbers:");<br>        findNarcissisticNumbers();<br>    }<br>    <br>    public static void findNarcissisticNumbers() {<br>        for (int num = 100; num < 1000; num++) {<br>            int original = num;<br>            int sum = 0;<br>            <br>            while (original > 0) {<br>                int digit = original % 10;<br>                sum += digit * digit * digit;<br>                original /= 10;<br>            }<br>            <br>            if (sum == num) {<br>                System.out.println(num);<br>            }<br>        }<br>    }<br>}