diff --git a/src/fancymath/math.py b/src/fancymath/math.py
index eafeaf8..b807566 100644
--- a/src/fancymath/math.py
+++ b/src/fancymath/math.py
@@ -15,6 +15,14 @@ def fact(n: int) -> int:
         return n * fact(n - 1)
 
 
+def is_even(x):
+    return x % 2 == 0
+
+
+def is_odd(x):
+    return x % 2 == 1
+
+
 if __name__ == '__main__':
     n = 5
     assert fact(n) == 120
diff --git a/test/test_math.py b/test/test_math.py
new file mode 100644
index 0000000..e69de29
diff --git a/test/test_util.py b/test/test_util.py
new file mode 100644
index 0000000..e69de29
diff --git a/test/test_vector.py b/test/test_vector.py
new file mode 100644
index 0000000..e69de29