Added Factorial calculation programm

Author: RomanHotsiy

Numbers/Factorial.java

@@ -0,0 +1,50 @@
+/**
+ * **Factorial Finder** - The Factorial of a positive integer, n, 
+ * is defined as the product of the sequence n, n-1, n-2, ...1 and the 
+ * factorial of zero, 0, is defined as being 1. 
+ * Solve this using both loops and recursion. 
+ */
+
+import java.io.*;
+import java.math.*;
+
+public class Factorial {
+	
+	private static BigInteger calcRecursive(int n){
+		if (n==0) 
+			return BigInteger.valueOf(1);
+		else if (n==1) 
+			return BigInteger.valueOf(1);
+		else
+			return calcRecursive(n-1).multiply(BigInteger.valueOf(n));
+	}
+	
+	private static BigInteger calcLoop(int n) {
+		BigInteger result = BigInteger.valueOf(1);
+		for(int i=n; i>1; i--)
+		{
+			result = result.multiply(BigInteger.valueOf(i));
+		}
+		return result;
+	}
+	
+	public static void main(String args[]) throws IOException{
+		System.out.println("Factorial calculator. Enter n: ");
+		int userAns=10;
+		BigInteger result;
+		try(BufferedReader br = new BufferedReader(new InputStreamReader(System.in))){
+			userAns = Integer.parseInt(br.readLine());
+		
+		
+			System.out.print("Recurcive? (y/N): ");
+			if (br.readLine().toLowerCase().equals("y")) {
+				result = calcRecursive(userAns);
+			} else {
+				result = calcLoop(userAns);
+			}
+		}
+		
+		System.out.printf("Result: %d! = ",userAns);
+		System.out.println(result.toString());
+	}
+}