Task1 Complete.

src/AssessmentPartOne.java

@@ -42,10 +42,27 @@ public class AssessmentPartOne {
 		
 		// You should comment your code explaining what each part does
 		
-		int sumOfSquares = 0;
+		int sumOfSquares = 0; //Defines and initialises the total value.
 		
+		if (start < end-1) { //Validates whether there are any numbers between the start and end and whether the start value is less than the end value.
+			if (!(start < 0) || (end < 0)) { //Validates that both the start and end values are not negative numbers.
 				
-		return sumOfSquares;
+				//Adds up all values from the start to the end exclusive of themselves.
+				for(int i=start+1;i<end;i++) {
+					sumOfSquares = sumOfSquares + i;
+				}
+				
+			}
+			else { //If the start and end value is a negative number.
+				sumOfSquares = -1; //Sets the sumOfSquares to -1; indicating that the calculation cannot be carried out.  
+			}
+		}
+		else { //If there are no values between the start and end or if the start value is less than the end value.
+			sumOfSquares = -1; //Sets the sumOfSquares to -1; indicating that the calculation cannot be carried out.
+		}
+		
+		
+		return sumOfSquares; //Returns the value.
 	}
 	
 }