diff --git a/.gitignore b/.gitignore
index 539bdba..7345e19 100644
--- a/.gitignore
+++ b/.gitignore
@@ -53,4 +53,11 @@ local.properties
 # Scala IDE specific (Scala & Java development for Eclipse)
 .cache-main
 .scala_dependencies
-.worksheet
\ No newline at end of file
+.worksheet
+*.xml
+
+# IDE folders
+.idea/
+
+#iml
+GitAssignmentObserver.iml
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..100deff
--- /dev/null
+++ b/README.md
@@ -0,0 +1,14 @@
+# Git Assignment for Team 15
+
+| Name        | ID           | Task  | Completed? | Bonus Design? |
+| ----------- | ------------ | ----- | ---------- | ------------- |
+| @Moustafa878 | 20170285 | SphereArea | :heavy_check_mark: | :x: |
+| @devmagdyy | 20160219 | MultiplicationSeries | :heavy_check_mark: | :heavy_check_mark: |
+| @amrmagdy12 | 20170188 | Fibonacci | :heavy_check_mark: | :heavy_check_mark: |
+| @Marim-medhat | 20170282 | CircleArea | :heavy_check_mark: | :heavy_check_mark: |
+| @AbdulelahAdam | 20170416 | SphereVolume | :heavy_check_mark: | :heavy_check_mark: |
+| @mahmoud-mohamed-abozied | 20170270 | SummationSeries | :heavy_check_mark: | :heavy_check_mark: |
+| @Abdulazizsayed | 20170154 | 2PowerN | :heavy_check_mark: | :x: |
+| @ahmed-dardery | 20170034 | SphereCircumference | :heavy_check_mark: | :heavy_check_mark: |
+| @Mina1998 | 20170307 | CircleVolume | :heavy_check_mark: | :heavy_check_mark: |
+| @fatima196 | 20170193 | CircleCircumference | :heavy_check_mark: | :heavy_check_mark: |
diff --git a/src/CircleArea.java b/src/CircleArea.java
new file mode 100644
index 0000000..7c7c501
--- /dev/null
+++ b/src/CircleArea.java
@@ -0,0 +1,16 @@
+public class CircleArea extends DoubleSubscriber { 
+ @Override
+    public void preProcess(int input) throws Exception {
+        System.out.print("Hello, I'm CircleArea , and I'm notified with: " + input + " as radius. ");
+        if (input < 0) throw new Exception("Negative radius is invalid!"); }
+  
+	 @Override
+    public double doCalculation(int input) {
+       return  Math.PI * input *input;
+    }
+
+    @Override
+    public void printAnswer(double output) {
+       System.out.println("Circle Area is: " + output);
+   }   
+}
diff --git a/src/CircleCircumference.java b/src/CircleCircumference.java
new file mode 100644
index 0000000..393ab55
--- /dev/null
+++ b/src/CircleCircumference.java
@@ -0,0 +1,17 @@
+public class CircleCircumference extends DoubleSubscriber {
+    
+    @Override
+    public void preProcess(int input) throws Exception {
+        System.out.print("Hello, I'm CircleCircumference, and I'm notified with: " + input + " as radius. ");
+        if (input < 0) throw new Exception("Negative radius is invalid!"); }
+
+    @Override
+    public double doCalculation(int input) {
+       return 2 * Math.PI * input;
+    }
+
+    @Override
+    public void printAnswer(double output) {
+       System.out.println("Circle Circumference is: " + output);
+   }   
+}
\ No newline at end of file
diff --git a/src/CircleVolume.java b/src/CircleVolume.java
new file mode 100644
index 0000000..4c2269f
--- /dev/null
+++ b/src/CircleVolume.java
@@ -0,0 +1,17 @@
+public class CircleVolume extends DoubleSubscriber {
+	@Override
+    public void preProcess(int input) throws Exception {
+        System.out.print("Hello, I'm CircleVolume, and I'm notified with: " + input + " as radius. ");
+        if (input < 0) throw new Exception("Negative radius is invalid!");
+    }
+
+    public double doCalculation(int input) {
+        return (4.0 / 3.0) * Math.PI * Math.pow(input, 3);
+    }
+
+    @Override
+    public void printAnswer(double output) {
+        System.out.println("Circle Volume is: " + output);
+    }
+
+}
diff --git a/src/DoubleSubscriber.java b/src/DoubleSubscriber.java
new file mode 100644
index 0000000..954466e
--- /dev/null
+++ b/src/DoubleSubscriber.java
@@ -0,0 +1,13 @@
+public abstract class DoubleSubscriber implements ISubscriber {
+    public void notifySubscriber(int input) throws Exception {
+        preProcess(input);
+        double ans = doCalculation(input);
+        printAnswer(ans);
+    }
+
+    public abstract void preProcess(int input) throws Exception;
+
+    public abstract double doCalculation(int input);
+
+    public abstract void printAnswer(double output);
+}
diff --git a/src/Fibonacci.java b/src/Fibonacci.java
new file mode 100644
index 0000000..8fb5672
--- /dev/null
+++ b/src/Fibonacci.java
@@ -0,0 +1,49 @@
+public class Fibonacci extends IntegerSubscriber{
+
+	@Override
+	public void preProcess(int input) throws Exception {
+
+		if(input < 1 ) throw new Exception("0 and Negative values are invalid ") ;
+
+		System.out.println("I'am Fibonnacii and I'am notified with >> " + input);
+	}
+
+	@Override
+	public int doCalculation(int n) {
+
+		if (n == 1 || n == 2) return 1 ;
+
+		int pascTriangle[][]  =  new int [n][n] ;
+
+		// drawing pascal's triangle as a base for Fibonnacii
+
+			for (int i = 2; i < n; i++) {
+				pascTriangle[i][0] = 1;
+				for (int j = 1; j <= i; j++) {
+					pascTriangle[i][j] = pascTriangle[i - 1][j - 1] + pascTriangle[i - 1][j];
+				}
+				pascTriangle[i][i] = 1;
+			}
+
+			int i = n - 1;
+			int j = 0;
+			int result = 0;
+
+			while (j <= i)
+			{
+				result += pascTriangle[i][j];
+				i--;
+				j++;
+
+			}
+
+			return result ;
+
+		}
+
+	@Override
+	public void printAnswer(int out) {
+
+		System.out.println("the answer is " + out );
+	}
+}
diff --git a/src/ISubscriber.java b/src/ISubscriber.java
index d3a605c..bc7bb57 100644
--- a/src/ISubscriber.java
+++ b/src/ISubscriber.java
@@ -1,4 +1,4 @@
 
 public interface ISubscriber {
-	public abstract void notifySubscriber(String input);
+    public abstract void notifySubscriber(int input) throws Exception;
 }
diff --git a/src/IntegerSubscriber.java b/src/IntegerSubscriber.java
new file mode 100644
index 0000000..32e28e3
--- /dev/null
+++ b/src/IntegerSubscriber.java
@@ -0,0 +1,13 @@
+public abstract class IntegerSubscriber implements ISubscriber {
+    public void notifySubscriber(int input) throws Exception {
+        preProcess(input);
+        int ans = doCalculation(input);
+        printAnswer(ans);
+    }
+
+    public abstract void preProcess(int input) throws Exception;
+
+    public abstract int doCalculation(int input);
+
+    public abstract void printAnswer(int output);
+}
diff --git a/src/Main.java b/src/Main.java
index 9b8c2b0..3587ba3 100644
--- a/src/Main.java
+++ b/src/Main.java
@@ -1,17 +1,59 @@
 import java.util.Scanner;
 
 public class Main {
-	private static ISubscriber subscribers [] = {
-			new SimpleSubscriber(),
-			new ReallySimpleSubscriber(),
-	};
-	public static void main(String[] args) {
-		Topic mathTopic = new Topic();
-		for (ISubscriber sub : subscribers) {
-			mathTopic.addSubscriber(sub);
-		}
-		Scanner sc = new Scanner(System.in);
-		String input = sc.next();
-		mathTopic.dispatchEvent(input);
-	}
-}
+    private static ISubscriber subscribers[] = {
+            new MultiplicationSeries(),
+            new SummationSeries(),
+
+            new CircleCircumference(),
+            new CircleArea(),
+            new CircleVolume(),
+
+            new SphereCircumference(),
+            new SphereArea(),
+            new SphereVolume(),
+
+            new Fibonacci(),
+            new TwoPowerN(),
+    };
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        Topic mathTopic = new Topic();
+        for (ISubscriber sub : subscribers) {
+            mathTopic.addSubscriber(sub);
+        }
+
+        try {
+            while (true) {
+
+
+                for (int i = 0; i < subscribers.length; ++i) {
+                    System.out.println((i + 1) + " - " + subscribers[i].getClass().getName());
+                }
+                System.out.println("0 - Run all functions");
+                System.out.println("X - Exit application");
+
+                System.out.println("Choose your option:");
+                String input = sc.next();
+                if (input.equals("X")) break;
+                int choice = Integer.parseInt(input);
+
+                System.out.println("Enter input number: ");
+                int n = Integer.parseInt(sc.next());
+
+                if (choice < 0 || choice > subscribers.length) throw new Exception("Invalid choice.");
+                if (choice != 0)
+                    subscribers[choice - 1].notifySubscriber(n);
+                else
+                    mathTopic.dispatchEvent(n);
+
+            }
+        } catch (NumberFormatException ignored) {
+            System.out.println("Your input is not a valid integer.");
+        } catch (Exception ex) {
+            System.out.println(ex.getMessage());
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/MultiplicationSeries.java b/src/MultiplicationSeries.java
new file mode 100644
index 0000000..89a3c7f
--- /dev/null
+++ b/src/MultiplicationSeries.java
@@ -0,0 +1,22 @@
+public class MultiplicationSeries extends IntegerSubscriber {
+
+    @Override
+    public void preProcess(int input) throws Exception {
+        System.out.println("Hello, I'm MultiplicationSeries, and I'm notified with: " + input + " as input. ");
+        if (input < 0) throw new Exception("Negative input is invalid!");
+    }
+
+    @Override
+    public int doCalculation(int input) {
+        int result = 1;
+        for (int i = 1; i <= input; i++) {
+            result = result * i;
+        }
+        return result;
+    }
+
+    @Override
+    public void printAnswer(int output) {
+        System.out.println("The Multiplication Series = " + output);
+    }
+}
\ No newline at end of file
diff --git a/src/ReallySimpleSubscriber.java b/src/ReallySimpleSubscriber.java
deleted file mode 100644
index fb1114a..0000000
--- a/src/ReallySimpleSubscriber.java
+++ /dev/null
@@ -1,8 +0,0 @@
-
-public class ReallySimpleSubscriber implements ISubscriber {
-	@Override
-	public void notifySubscriber(String input) {
-		// TODO Auto-generated method stub
-		System.out.println("Hello, I am really a simple subscriber and I am notified with " + input);
-	}
-}
diff --git a/src/SimpleSubscriber.java b/src/SimpleSubscriber.java
deleted file mode 100644
index 5b0e4aa..0000000
--- a/src/SimpleSubscriber.java
+++ /dev/null
@@ -1,10 +0,0 @@
-
-public class SimpleSubscriber implements ISubscriber {
-
-	@Override
-	public void notifySubscriber(String input) {
-		// TODO Auto-generated method stub
-		System.out.println("Hello, I am a simple subscriber and I am notified with " + input);
-	}
-
-}
diff --git a/src/SphereArea.java b/src/SphereArea.java
new file mode 100644
index 0000000..2eef3ce
--- /dev/null
+++ b/src/SphereArea.java
@@ -0,0 +1,16 @@
+
+public class SphereArea implements ISubscriber {
+    @Override
+    public void notifySubscriber(int input) {
+
+
+        double radius = input;
+        double Area = 4 * (Math.PI) * Math.pow(radius, 2);
+        System.out.println("The Area of Sphere = " + Area + " square meters");
+
+
+    }
+
+}
+
+
diff --git a/src/SphereCircumference.java b/src/SphereCircumference.java
new file mode 100644
index 0000000..6b6868c
--- /dev/null
+++ b/src/SphereCircumference.java
@@ -0,0 +1,16 @@
+public class SphereCircumference extends DoubleSubscriber {
+    @Override
+    public void preProcess(int input) throws Exception {
+        System.out.print("Hello, I'm SphereCircumference, and I'm notified with: " + input + " as radius. ");
+        if (input < 0) throw new Exception("Negative radius is invalid!");
+    }
+
+    public double doCalculation(int input) {
+        return 2 * Math.PI * input;
+    }
+
+    @Override
+    public void printAnswer(double output) {
+        System.out.println("Sphere Circumference is: " + output);
+    }
+}
\ No newline at end of file
diff --git a/src/SphereVolume.java b/src/SphereVolume.java
new file mode 100644
index 0000000..950e542
--- /dev/null
+++ b/src/SphereVolume.java
@@ -0,0 +1,34 @@
+import java.lang.Math;
+public class SphereVolume extends DoubleSubscriber {
+
+	private static double value = 4.0/3.0;
+	
+	@Override
+	public void preProcess(int input) throws Exception {
+		 System.out.print("Hello, I'm SphereVolume, and I'm notified with: " + input + " as radius. ");
+	        if (input < 0) throw new Exception("Negative radius is invalid!");
+		
+	}
+
+
+
+	@Override
+	public double doCalculation(int input) {
+		return value*(Math.PI)*Math.pow(input, 3);
+		
+	}
+
+
+
+	@Override
+	public void printAnswer(double output) {
+		System.out.println("Sphere Volume is: " + output);
+
+		
+	}
+
+
+	
+
+
+}
diff --git a/src/SummationSeries.java b/src/SummationSeries.java
new file mode 100644
index 0000000..36fd5d3
--- /dev/null
+++ b/src/SummationSeries.java
@@ -0,0 +1,19 @@
+public class SummationSeries extends IntegerSubscriber {
+
+	@Override
+	public void preProcess(int input) throws Exception {
+		System.out.print("Hello, I'm SummationSeries, and I'm notified with: " + input + " as input. ");
+        if (input < 0) throw new Exception("Negative input is invalid!");
+    }
+
+	@Override
+	public int doCalculation(int input) {
+		return (input * (input + 1)) / 2;
+	}
+
+	@Override
+	public void printAnswer(int output) {
+		System.out.println("The Summation Series = " + output);
+	}
+
+}
diff --git a/src/Topic.java b/src/Topic.java
index 8fa2e2e..f234958 100644
--- a/src/Topic.java
+++ b/src/Topic.java
@@ -2,24 +2,28 @@
 import java.util.List;
 
 public class Topic {
-	
-	private List<ISubscriber> subscribers;
-	
-	public Topic() {
-		subscribers = new ArrayList<ISubscriber>();
-	}
-	
-	public void addSubscriber(ISubscriber sub) {
-		subscribers.add(sub);
-	}
-	
-	public List<ISubscriber> getSubscribers() {
-		return subscribers;
-	}
-	
-	public void dispatchEvent(String input) {
-		for (ISubscriber sub : this.getSubscribers()) {
-			sub.notifySubscriber(input);
-		}
-	}
+
+    private List<ISubscriber> subscribers;
+
+    public Topic() {
+        subscribers = new ArrayList<ISubscriber>();
+    }
+
+    public void addSubscriber(ISubscriber sub) {
+        subscribers.add(sub);
+    }
+
+    public List<ISubscriber> getSubscribers() {
+        return subscribers;
+    }
+
+    public void dispatchEvent(int input) {
+        for (ISubscriber sub : this.getSubscribers()) {
+            try {
+                sub.notifySubscriber(input);
+            } catch (Exception ex) {
+                System.out.println(ex.getMessage());
+            }
+        }
+    }
 }
diff --git a/src/TwoPowerN.java b/src/TwoPowerN.java
new file mode 100644
index 0000000..6fd5f82
--- /dev/null
+++ b/src/TwoPowerN.java
@@ -0,0 +1,13 @@
+
+public class TwoPowerN implements ISubscriber {
+    @Override
+    public void notifySubscriber(int input) {
+        int p = input, res = 2;
+
+        for (int i = 1; i < p; i++) {
+            res += res;
+        }
+
+        System.out.println("Two power N is " + res);
+    }
+}
\ No newline at end of file