diff --git a/project_euler/problem_08/sol1.py b/project_euler/problem_08/sol1.py
index 1cccdb8c85d6..ed9070cf37d0 100644
--- a/project_euler/problem_08/sol1.py
+++ b/project_euler/problem_08/sol1.py
@@ -50,7 +50,7 @@
 71636269561882670428252483600823257530420752963450"""
 
 
-def solution(n):
+def solution(n: str = N):
     """Find the thirteen adjacent digits in the 1000-digit number n that have
     the greatest product and returns it.
 
@@ -68,4 +68,4 @@ def solution(n):
 
 
 if __name__ == "__main__":
-    print(solution(N))
+    print(solution())
diff --git a/project_euler/problem_08/sol2.py b/project_euler/problem_08/sol2.py
index 60bd8254f2c3..b7c6d2d27406 100644
--- a/project_euler/problem_08/sol2.py
+++ b/project_euler/problem_08/sol2.py
@@ -53,7 +53,7 @@
 )
 
 
-def solution(n):
+def solution(n=str(N)):
     """Find the thirteen adjacent digits in the 1000-digit number n that have
     the greatest product and returns it.
 
@@ -69,4 +69,4 @@ def solution(n):
 
 
 if __name__ == "__main__":
-    print(solution(str(N)))
+    print(solution())
diff --git a/project_euler/problem_08/sol3.py b/project_euler/problem_08/sol3.py
index f3e87c6d3436..6df61b944433 100644
--- a/project_euler/problem_08/sol3.py
+++ b/project_euler/problem_08/sol3.py
@@ -57,7 +57,7 @@ def streval(s: str) -> int:
     return ret
 
 
-def solution(n: str) -> int:
+def solution(n: str = N) -> int:
     """Find the thirteen adjacent digits in the 1000-digit number n that have
     the greatest product and returns it.
 
@@ -79,4 +79,4 @@ def solution(n: str) -> int:
 
 
 if __name__ == "__main__":
-    print(solution(N))
+    print(solution())