adding the remove digit algorithm

maths/remove_digit.py

@@ -0,0 +1,42 @@
+def remove_digit(num: int) -> int:
+    """
+
+    returns the biggest possible result
+    that can be achieved by removing
+    one digit from the given number
+
+    >>> remove_digit(152)
+    52
+    >>> remove_digit(6385)
+    685
+    >>> remove_digit(-11)
+    1
+    >>> remove_digit(2222222)
+    222222
+    >>> remove_digit("2222222")
+    Traceback (most recent call last):
+    TypeError: only integers accepted as input
+    >>> remove_digit("string input")
+    Traceback (most recent call last):
+    TypeError: only integers accepted as input
+    """
+
+    if isinstance(num, int):
+        num_str = str(abs(num))
+        num_transpositions = [
+            [char for char in num_str] for char in range(len(num_str))
+        ]
+        for index in range(len(num_str)):
+            num_transpositions[index].pop(index)
+        return sorted(
+                 int("".join([char for char in transposition]))
+                for transposition in num_transpositions,
+                reverse=True
+            ]
+        )[0]
+    else:
+        raise TypeError("only integers accepted as input")
+
+
+if __name__ == "__main__":
+    __import__("doctest").testmod()