diff --git a/bit_manipulation/count_bits.py b/bit_manipulation/count_bits.py
new file mode 100644
index 000000000000..cebd165b4da1
--- /dev/null
+++ b/bit_manipulation/count_bits.py
@@ -0,0 +1,32 @@
+def count_bits(n: int) -> int:
+    """
+    Count the number of set bits (1s) in the binary representation of a
+    non-negative integer.
+
+    Examples:
+    >>> count_bits(0)
+    0
+    >>> count_bits(1)
+    1
+    >>> count_bits(5)  # 101
+    2
+    >>> count_bits(15)  # 1111
+    4
+    >>> count_bits(16)  # 10000
+    1
+    """
+    if n < 0:
+        raise ValueError("Input must be non-negative")
+
+    count = 0
+    while n > 0:
+        count += n & 1
+        n >>= 1
+
+    return count
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
diff --git a/strings/integer_to_roman.py b/strings/integer_to_roman.py
new file mode 100644
index 000000000000..95de2d9158c8
--- /dev/null
+++ b/strings/integer_to_roman.py
@@ -0,0 +1,52 @@
+def integer_to_roman(n: int) -> str:
+    """
+    Convert an integer to a Roman numeral.
+
+    Examples:
+    >>> integer_to_roman(1)
+    'I'
+    >>> integer_to_roman(4)
+    'IV'
+    >>> integer_to_roman(9)
+    'IX'
+    >>> integer_to_roman(58)
+    'LVIII'
+    >>> integer_to_roman(1994)
+    'MCMXCIV'
+    >>> integer_to_roman(0)
+    Traceback (most recent call last):
+        ...
+    ValueError: number must be between 1 and 3999
+    """
+    if not (1 <= n <= 3999):
+        raise ValueError("number must be between 1 and 3999")
+
+    symbols = [
+        (1000, "M"),
+        (900, "CM"),
+        (500, "D"),
+        (400, "CD"),
+        (100, "C"),
+        (90, "XC"),
+        (50, "L"),
+        (40, "XL"),
+        (10, "X"),
+        (9, "IX"),
+        (5, "V"),
+        (4, "IV"),
+        (1, "I"),
+    ]
+
+    result = []
+    for value, numeral in symbols:
+        while n >= value:
+            result.append(numeral)
+            n -= value
+
+    return "".join(result)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()