remove Calculator interface

src/main/java/com/ap/BasicCalculator.java

@@ -12,8 +12,7 @@ public class BasicCalculator implements Calculator {
     }
 
     @Override
-    public int multiply(int a, int b) {
+    public int product(int a, int b) {
-        int m = a * b;
+        return a * b;
-        return m;
     }
 }

src/main/java/com/ap/Calculator.java

@@ -1,7 +0,0 @@
-package com.ap;
-
-public interface Calculator {
-    int add(int a, int b);
-    int subtract(int a, int b);
-    int multiply(int a, int b);
-}

src/main/java/com/ap/MathHelper.java

@@ -1,7 +1,7 @@
 package com.ap;
 
 public class MathHelper {
-    public static int multiply(int a, int b) {
+    public static int product(int a, int b) {
         return a * b;
     }
 

src/main/java/com/ap/ReportGenerator.java

@@ -5,7 +5,7 @@ public class ReportGenerator {
         Calculator calc = new BasicCalculator();
         int sum = calc.add(x, y);
         int diff = calc.subtract(x, y);
-        int product = calc.multiply(x, y);
+        int product = calc.product(x, y);
         int max = MathHelper.max(x, y);
         System.out.println("Sum: " + sum + ", Diff: " + diff +
                 ", Product: " + product + ", Max: " + max);

src/test/java/CalculatorTest.java

@@ -19,8 +19,8 @@ public class CalculatorTest {
     }
 
     @Test
-    void testMultiply() {
+    void testProduct() {
         Calculator calc = new BasicCalculator();
-        assertEquals(6, calc.multiply(2, 3));
+        assertEquals(6, calc.product(2, 3));
     }
 }