diff --git a/tests/test_base.py b/tests/test_base.py
index efa1bc81..7d0cbd7d 100644
--- a/tests/test_base.py
+++ b/tests/test_base.py
@@ -62,3 +62,56 @@ def test_is_title(self):
             self.base.title("one"),
             "one"
             )
+
+    def test_set_high_numwords_not_implemented(self):
+        with self.assertRaises(NotImplementedError):
+            self.base.set_high_numwords()
+
+class SplitNumTest(TestCase):
+    def setUp(self):
+        self.base = Num2Word_Base()
+
+    def test_splitnum_zero(self):
+        value = 0
+        expected = []
+        result = self.base.splitnum(value)
+        self.assertEqual(result, expected)
+
+    def test_splitnum_single_digit(self):
+        value = 5
+        expected = [('five', 5)]
+        result = self.base.splitnum(value)
+        self.assertEqual(result, expected)
+
+    def test_splitnum_multiple_digits(self):
+        value = 1234
+        expected = [('one thousand', 1000),
+                    ('two hundred', 100),
+                    ('thirty', 10),
+                    ('four', 1)]
+        result = self.base.splitnum(value)
+        self.assertEqual(result, expected)
+
+    def test_splitnum_decimal(self):
+        value = Decimal('1234.56')
+        expected = [('one thousand', 1000),
+                    ('two hundred', 100),
+                    ('thirty', 10), ('four', 1),
+                    ('point', 0), ('five', Decimal('0.5')),
+                    ('six', Decimal('0.06'))]
+        result = self.base.splitnum(value)
+        self.assertEqual(result, expected)
+
+    def test_splitnum_large_value(self):
+        value = 9876543210
+        expected = [('nine billion', 1000000000),
+                    ('eight hundred', 100000000),
+                    ('seventy', 10000000),
+                    ('six million', 1000000),
+                    ('five hundred', 100000),
+                    ('forty', 10000),
+                    ('three thousand', 1000),
+                    ('two hundred', 100),
+                    ('ten', 10)]
+        result = self.base.splitnum(value)
+        self.assertEqual(result, expected)