public void ValidateThirdSubstracting()
        {
            int [] sequence;
            bool   validates;

            // Invalid Formula.ThirdSubstracting sequence
            // since it validates 7 + 10 = -3 but (ThirdSubstracting) also 7 + 10 -3 = 7 + 2 + 5 (adding the numbers)
            sequence  = new [] { 7, 10, -3, 6, 8, -2, 7, 2, 5 };
            validates = PuzzleNumericRelation.Validate(sequence, PuzzleNumericRelation.Formula.ThirdSubstracting, 5);
            Assert.AreEqual(false, validates);

            // Valid Formula.ThirdSubstracting sequence
            sequence  = new [] { 7, 10, -3, 6, 8, -2, 7, 2, 6 };
            validates = PuzzleNumericRelation.Validate(sequence, PuzzleNumericRelation.Formula.ThirdSubstracting, 5);
            Assert.AreEqual(true, validates);
        }
        public void ValidateAllAdding()
        {
            int [] sequence;
            bool   validates;

            // Invalid Formula.AllAdding sequence
            // since it validates 6 + 9 + 15 = 30, 1 + 6 + 23, 4 + 11 + 15 = 30 (Adding the numbers)
            // but (ThirdSubstracting) also 6 + 9 = 15, 4 + 11 = 15
            sequence  = new [] { 6, 9, 15, 1, 6, 23, 4, 11, 15 };
            validates = PuzzleNumericRelation.Validate(sequence, PuzzleNumericRelation.Formula.AllAdding, 4);
            Assert.AreEqual(false, validates);

            // Valid Formula.AllAdding sequence
            sequence  = new [] { 6, 9, 14, 1, 5, 23, 4, 11, 14 };
            validates = PuzzleNumericRelation.Validate(sequence, PuzzleNumericRelation.Formula.AllAdding, 4);
            Assert.AreEqual(true, validates);
        }