Added the calculator.java

Author: Arfanjaman

myaddition/Calculator.java

@@ -0,0 +1,6 @@
+public class Calculator {
+    public int add(int a, int b){ return a + b; }
+    public int subtract(int a, int b){ return a - b; }
+    public int multiply(int a, int b){ return a * b; }
+    public double divide(int a, int b){ return (double)a / b; }
+}