> For the complete documentation index, see [llms.txt](https://vives.gitbook.io/oop-with-java/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://vives.gitbook.io/oop-with-java/storing-and-processing-data/challenges.md).

# Challenges

## Chapter 04 - Storing and processing data - Challenges

### Data Types

In the most left column is a piece of data that is stored inside of the computers memory. What would be a possible data type for each piece of information? In some cases multiple data types would be valid.

| Data                           | int | double | boolean | char | String |
| ------------------------------ | --- | ------ | ------- | ---- | ------ |
| 128                            | \[] | \[]    | \[]     | \[]  | \[]    |
| -12                            | \[] | \[]    | \[]     | \[]  | \[]    |
| a                              | \[] | \[]    | \[]     | \[]  | \[]    |
| Hello World                    | \[] | \[]    | \[]     | \[]  | \[]    |
| 108.6                          | \[] | \[]    | \[]     | \[]  | \[]    |
| true                           | \[] | \[]    | \[]     | \[]  | \[]    |
| Spoorwegstraat 12, 8200 Brugge | \[] | \[]    | \[]     | \[]  | \[]    |
| A                              | \[] | \[]    | \[]     | \[]  | \[]    |
| 0471 11 18 23                  | \[] | \[]    | \[]     | \[]  | \[]    |
| 3.14                           | \[] | \[]    | \[]     | \[]  | \[]    |
| x                              | \[] | \[]    | \[]     | \[]  | \[]    |
| ZZ Top                         | \[] | \[]    | \[]     | \[]  | \[]    |
| false                          | \[] | \[]    | \[]     | \[]  | \[]    |
| -778.81323                     | \[] | \[]    | \[]     | \[]  | \[]    |

### Basic Division

Determine the result of 2 divided by 3. Next try out 2.0 divided by 3.

### Floating Point Division

Take the code below and execute it:

```java
int a = 5;
int b = 2;

double result = a / b;
```

How can you change only the last line to get a result of `2.5`?

### Remainder

What is the remainder of 8759 divided by 33?

### Calculating VAT

When buying a product in the store you always need to pay VAT (taxes). Take for example a pair of shoes that costs 100eur net, you actually pay 121eur.

Write a program that calculates how much the total bill would be if the net amount is 250eur.

### Rectangle Area

Determine the area of a rectangle with a side of 2.3cm and a side of 8.2cm. Make your program outputs a decent result to the user.

### String Concatenation

Take the code below and change the variable `fullText` to contain all partial strings before it.

```java
String hello = "Hello sir/madam on this fine day of learning.";
String hackerspace = "I would like to inform you that there will be hackerspace on tuesdays and thursdays.";
String attend = "Feel free to attend it as it will be fun for all.";

String fullText;
```

Print out the variable `fullText` so the whole message is shown to the user.

## Circle Properties

Write a Java program to determine the area and circumference of a circle. They can be calculated using the formulas below:

```
area = radius x radius x pi
circumference = 2 x radius x pi
```

Make sure all the variables are of type `double`.

Print all the parameters to the terminal (radius, diameter, area and circumference) so the user had a nice overview. For example:

```
Hello and welcome to the Circle Properties app.

Properties of circle:
- radius: 2.15 meters
- diameter: 4.30 meters
- circumference: 13.51 meters
- area: 14.52 square meters

Thank you for using the app.
```

You can create a variable to hold an approximation to the value of pi. However, Java can supply a more accurate version of PI. Can you find on the Internet how to access/use this value?

### Concatenation and Addition

Explain the difference in output between the following two lines of code:

```java
System.out.println("Berekening 1: " + 12 + 88);
System.out.println("Berekening 2: " + (12 + 88));
```