public void CalculateIndexOfMillionTests()
        {
            // Arrange

            // Act
            var secondWord = converterHelper.CalculateIndexOfMillion(new string[] { "one", "million" });
            var notFound   = converterHelper.CalculateIndexOfMillion(new string[] { "one", "hundred", "thousand" });

            // Assert
            Assert.AreEqual(1, secondWord);
            Assert.AreEqual(-1, notFound);
        }