> For the complete documentation index, see [llms.txt](https://peterlulu666.gitbook.io/tek-system-java-developer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://peterlulu666.gitbook.io/tek-system-java-developer/week-3/practice-assignment/loops.md).

# Loops

### Objective:

In this assignment, you will create a Java program. Requirements are given below. This assignment will test your knowledge of Control Flow (Conditional) Statements and loops in Java.

### Tasks:

#### 1: Print a Multiplication Table

Write a program that uses nested for loops to print a multiplication table.

| 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9   | 10  | 11  | 12  |
| -- | -- | -- | -- | -- | -- | -- | -- | --- | --- | --- | --- |
| 2  | 4  | 6  | 8  | 10 | 12 | 14 | 16 | 18  | 20  | 22  | 24  |
| 3  | 6  | 9  | 12 | 15 | 18 | 21 | 24 | 27  | 30  | 33  | 36  |
| 4  | 8  | 12 | 16 | 20 | 24 | 28 | 32 | 36  | 40  | 44  | 48  |
| 5  | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45  | 50  | 55  | 60  |
| 6  | 12 | 18 | 24 | 30 | 36 | 42 | 48 | 54  | 60  | 66  | 72  |
| 7  | 14 | 21 | 28 | 35 | 42 | 49 | 56 | 63  | 70  | 77  | 84  |
| 8  | 16 | 24 | 32 | 40 | 48 | 56 | 64 | 72  | 80  | 88  | 96  |
| 9  | 18 | 27 | 36 | 45 | 54 | 63 | 72 | 81  | 90  | 99  | 108 |
| 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90  | 100 | 110 | 120 |
| 11 | 22 | 33 | 44 | 55 | 66 | 77 | 88 | 99  | 110 | 121 | 132 |
| 12 | 24 | 36 | 48 | 60 | 72 | 84 | 96 | 108 | 120 | 132 | 144 |

#### 2: Find the Greatest Common Divisor

Write a program that prompts the user to enter two positive integers, and find their greatest common divisor (GCD). 

* Examples: 
  * Enter 2 and 4. The gcd is 2. 
  * Enter 16 and 24. The gcd is 8. 
* How do you find the gcd? 
  * Name the two input integers n1 and n2. 
  * You know number 1 is a common divisor, but it may not be the gcd. 
  * Check whether k (for k = 2, 3, 4, and so on) is a common divisor for n1 and n2, until k is greater than n1 or n2. 

#### 3: Predict Future Tuition

Suppose the tuition for a university is $10,000 for the current year and increases by 7 percent every year. In how many years will the tuition be doubled?

| Year | Tuition                   |
| ---- | ------------------------- |
| 0    | $10,000                   |
| 1    | tuition = 1.07 \* tuition |
| ...  | tuition = 1.07 \* tuition |
| ...  | tuition = 1.07 \* tuition |
| ...  |                           |
| ...  | $20,000 or more           |

```java
package PracticeAssignment;

import java.util.Scanner;

public class Loops {
    public static void main(String[] args) {
        // Print a Multiplication Table
        for (int i = 1; i <= 12; i++) {
            for (int j = 1; j <= 12; j++) {
                System.out.print((i * j) + " ");
            }
            System.out.println();
        }

        // Find the Greatest Common Divisor
        Scanner input = new Scanner(System.in);
        System.out.print("Enter n1: ");
        int n1 = input.nextInt();
        System.out.print("Enter n2: ");
        int n2 = input.nextInt();
        int commonDivisor = 1;
        int k = 2;
        while (true) {
            if (k > n1 || k > n2) {
                break;
            }
            if (n1 % k == 0 && n2 % k == 0) {
                commonDivisor = k;
            }
            k ++;
        }
        System.out.println("The gcd is " + commonDivisor);

        // Predict Future Tuition
        double tuition = 10000;
        int year = 0;
        while (true) {
            if (tuition >= 20000) {
                break;
            }
            tuition = 1.07 * tuition;
            year++;
        }
        System.out.println("Year " + year);
    }
}
```