diff --git a/src/Python/Problems001-050/Problem017.py b/src/Python/Problems001-050/Problem017.py
index 48953ee..258ff94 100644
--- a/src/Python/Problems001-050/Problem017.py
+++ b/src/Python/Problems001-050/Problem017.py
@@ -11,14 +11,40 @@ https://projecteuler.net/problem=17
 
 from utils import timeit
 
+
 def num2letters(num):
-    nums = {0: '', 1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five',
-            6: 'six', 7: 'seven', 8: 'eight', 9: 'nine', 10: 'ten',
-            11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen',
-            15: 'fifteen', 16: 'sixteen', 17: 'seventeen', 18: 'eighteen',
-            19: 'nineteen', 20: 'twenty', 30: 'thirty', 40: 'forty',
-            50: 'fifty', 60: 'sixty', 70: 'seventy', 80: 'eighty',
-            90: 'ninety', 100: 'hundred', 1000: 'thousand'}
+    nums = {
+        0: "",
+        1: "one",
+        2: "two",
+        3: "three",
+        4: "four",
+        5: "five",
+        6: "six",
+        7: "seven",
+        8: "eight",
+        9: "nine",
+        10: "ten",
+        11: "eleven",
+        12: "twelve",
+        13: "thirteen",
+        14: "fourteen",
+        15: "fifteen",
+        16: "sixteen",
+        17: "seventeen",
+        18: "eighteen",
+        19: "nineteen",
+        20: "twenty",
+        30: "thirty",
+        40: "forty",
+        50: "fifty",
+        60: "sixty",
+        70: "seventy",
+        80: "eighty",
+        90: "ninety",
+        100: "hundred",
+        1000: "thousand",
+    }
 
     if num <= 20:
         return len(nums[num])
@@ -28,14 +54,16 @@ def num2letters(num):
     elif num < 1000:
         hundreds, rest = divmod(num, 100)
         if rest:
-            return num2letters(hundreds) + len(nums[100]) + len('and') +\
-                   num2letters(rest)
+            return (
+                num2letters(hundreds) + len(nums[100]) + len("and") + num2letters(rest)
+            )
         else:
             return num2letters(hundreds) + len(nums[100])
     else:
         thousands, rest = divmod(num, 1000)
         return num2letters(thousands) + len(nums[1000])
 
+
 @timeit("Problem 17")
 def compute():
     """
@@ -59,4 +87,4 @@ def compute():
 
 if __name__ == "__main__":
 
-    print(f"Result for Problem 17: {compute()}")
\ No newline at end of file
+    print(f"Result for Problem 17: {compute()}")