getting started

src/main/java/rocks/zipcode/calcskin/CalcEngine.java

     }
 
     public double add(double v, double v1) {
-        return Double.NaN;
+        double add = v + v1;
+        return add;
     }
 
     public double subtract(double v, double v1) {
         return Double.NaN;
     }
 
-    public double multiply(double v, double v1) {
+    public double multiply(double v, double v1)
+    {
         return Double.NaN;
     }
 
     public double divide(double v, double v1) {
+
         return Double.NaN;
     }
 }