diff --git a/ciphers/onepad_cipher.py b/ciphers/onepad_cipher.py
index 4bfe35b7180a..c4fb22e14a06 100644
--- a/ciphers/onepad_cipher.py
+++ b/ciphers/onepad_cipher.py
@@ -4,7 +4,27 @@
 class Onepad:
     @staticmethod
     def encrypt(text: str) -> tuple[list[int], list[int]]:
-        """Function to encrypt text using pseudo-random numbers"""
+        """
+        Function to encrypt text using pseudo-random numbers
+        >>> Onepad().encrypt("")
+        ([], [])
+        >>> Onepad().encrypt([])
+        ([], [])
+        >>> random.seed(1)
+        >>> Onepad().encrypt(" ")
+        ([6969], [69])
+        >>> random.seed(1)
+        >>> Onepad().encrypt("Hello")
+        ([9729, 114756, 4653, 31309, 10492], [69, 292, 33, 131, 61])
+        >>> Onepad().encrypt(1)
+        Traceback (most recent call last):
+        ...
+        TypeError: 'int' object is not iterable
+        >>> Onepad().encrypt(1.1)
+        Traceback (most recent call last):
+        ...
+        TypeError: 'float' object is not iterable
+        """
         plain = [ord(i) for i in text]
         key = []
         cipher = []
@@ -17,7 +37,20 @@ def encrypt(text: str) -> tuple[list[int], list[int]]:
 
     @staticmethod
     def decrypt(cipher: list[int], key: list[int]) -> str:
-        """Function to decrypt text using pseudo-random numbers."""
+        """
+        Function to decrypt text using pseudo-random numbers.
+        >>> Onepad().decrypt([], [])
+        ''
+        >>> Onepad().decrypt([35], [])
+        ''
+        >>> Onepad().decrypt([], [35])
+        Traceback (most recent call last):
+        ...
+        IndexError: list index out of range
+        >>> random.seed(1)
+        >>> Onepad().decrypt([9729, 114756, 4653, 31309, 10492], [69, 292, 33, 131, 61])
+        'Hello'
+        """
         plain = []
         for i in range(len(key)):
             p = int((cipher[i] - (key[i]) ** 2) / key[i])
diff --git a/maths/largest_of_very_large_numbers.py b/maths/largest_of_very_large_numbers.py
index 7e7fea004958..eb5c121fd262 100644
--- a/maths/largest_of_very_large_numbers.py
+++ b/maths/largest_of_very_large_numbers.py
@@ -4,6 +4,19 @@
 
 
 def res(x, y):
+    """
+    Reduces large number to a more manageable number
+    >>> res(5, 7)
+    4.892790030352132
+    >>> res(0, 5)
+    0
+    >>> res(3, 0)
+    1
+    >>> res(-1, 5)
+    Traceback (most recent call last):
+    ...
+    ValueError: math domain error
+    """
     if 0 not in (x, y):
         # We use the relation x^y = y*log10(x), where 10 is the base.
         return y * math.log10(x)
diff --git a/strings/word_patterns.py b/strings/word_patterns.py
index d12d267e7b35..ed603e9fefeb 100644
--- a/strings/word_patterns.py
+++ b/strings/word_patterns.py
@@ -1,11 +1,32 @@
 def get_word_pattern(word: str) -> str:
     """
+    Returns numerical pattern of character appearances in given word
+    >>> get_word_pattern("")
+    ''
+    >>> get_word_pattern(" ")
+    '0'
     >>> get_word_pattern("pattern")
     '0.1.2.2.3.4.5'
     >>> get_word_pattern("word pattern")
     '0.1.2.3.4.5.6.7.7.8.2.9'
     >>> get_word_pattern("get word pattern")
     '0.1.2.3.4.5.6.7.3.8.9.2.2.1.6.10'
+    >>> get_word_pattern()
+    Traceback (most recent call last):
+    ...
+    TypeError: get_word_pattern() missing 1 required positional argument: 'word'
+    >>> get_word_pattern(1)
+    Traceback (most recent call last):
+    ...
+    AttributeError: 'int' object has no attribute 'upper'
+    >>> get_word_pattern(1.1)
+    Traceback (most recent call last):
+    ...
+    AttributeError: 'float' object has no attribute 'upper'
+    >>> get_word_pattern([])
+    Traceback (most recent call last):
+    ...
+    AttributeError: 'list' object has no attribute 'upper'
     """
     word = word.upper()
     next_num = 0