Exercise Answers

Question 1:

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public class QuestionOne
{
   public static void main(String[] args)
   {
      //Display some messages on the console
      System.out.println("Hello World!");
      System.out.println("It is very nice to meet you.");
      System.out.println("This is one of my first Java programs.");
   }
}

Question 2:

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public class QuestionTwo
{
   public static void main(String[] args)
   {
      //Display message Robot on the console
      System.out.println("RRRRR    OOO    BBBBB    OOO   TTTTT");
      System.out.println(" R  R   O   O   B   B   O   O    T");
      System.out.println(" RRRR  O     O  BBBBB  O     O   T");
      System.out.println(" R  R   O   O   B   B   O   O    T");
      System.out.println("RR   R   OOO    BBBBB    OOO     T");
   }
}

Question 3:

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public class QuestionThree
{
    public static void main(String[] args)
    {
        //Display a table on the console
        System.out.println("x     x^2      x^3      x^4");
        System.out.println("1     1        1        1");
        System.out.println("2     4        8        16");
        System.out.println("3     9        27       81");
        System.out.println("4     16       64       256");
        System.out.println("5     25       125      625");
    }
}

Question 4:

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public class QuestionFour
{
    public static void main(String[] args)
    {
        //Display some math on the console
        System.out.print("1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = ");
        System.out.println(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9);
    }
}

Output

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45

Question 5:

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public class QuestionFive
{
    public static void main(String[] args)
    {
        //Display some math on the console
        System.out.println((10.6 * 4.0 - 3.2 * 1.0) / (20.6 - 1.8));
    }
}

Output

2.085106382978723

Question Six

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public class QuestionSix
{
    public static void main(String[] args)
    {
        //Display some math on the console
        System.out.print((9.0 / 5.0) * 30 + 32);
        System.out.println("°F");
    }
}

Output

86°F

Important

If you got 62°F as your answer there is a logic error in your code. In Java \(\begin{equation}\frac{9}{5}\end{equation}\) would result in 1. This is due to integer division. Integers do not allow decimal points. \(\begin{equation}\frac{9}{5}\end{equation}\) should be 1.8 but the result is 1 as .8 is discarded. To eliminate integer division we add .0 to the integer as shown in the answer.

Challenge Question

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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.edu.firstproject;

import java.util.Scanner;

/**
 *
 * @author james
 */
public class ChallengeQuestion
{
   public static void main(String[] args)
   {
      Scanner input = new Scanner(System.in);
      System.out.print("Enter the temperature to convert in °C: ");
      double temp = input.nextDouble();
      System.out.println(temp + "°C is equal to " + ((9.0 / 5.0) * temp + 32) + "°F");
   }
}

Example Output

Enter the temperature to covert in °C: 21.5
21.5°C is equal to 70.7°F