Adding FactorialOperation class

app/src/main/kotlin/com/simplemobiletools/calculator/operation/FactorialOperation.kt

@@ -0,0 +1,26 @@
+package com.simplemobiletools.calculator.operation
+
+import com.simplemobiletools.calculator.operation.base.BinaryOperation
+import com.simplemobiletools.calculator.operation.base.Operation
+import com.simplemobiletools.calculator.operation.base.UnaryOperation
+
+class ParOperation(value: Double) : UnaryOperation(value), Operation {
+
+    override fun getResult(): Double {
+        var result = 1.0
+        if (value==0.0 || value==1.0){
+            return result
+        }
+        else {
+            var base: Int
+            base = value.toInt()
+            for (i in 1..base){
+                //Find Factorial of a number using for loop
+                result *= i
+
+            }
+        }
+        return result
+
+    }
+}