diff --git a/project_euler/problem_02/sol1.py b/project_euler/problem_02/sol1.py
index ec89ddaeb..2acc93b0a 100644
--- a/project_euler/problem_02/sol1.py
+++ b/project_euler/problem_02/sol1.py
@@ -11,7 +11,7 @@ n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
 """
 
 
-def solution(n):
+def solution(n: int = 4000000) -> int:
     """Returns the sum of all fibonacci sequence even elements that are lower
     or equals to n.
 
@@ -28,13 +28,13 @@ def solution(n):
     """
     i = 1
     j = 2
-    sum = 0
+    total = 0
     while j <= n:
         if j % 2 == 0:
-            sum += j
+            total += j
         i, j = j, i + j
 
-    return sum
+    return total
 
 
 if __name__ == "__main__":
diff --git a/project_euler/problem_02/sol2.py b/project_euler/problem_02/sol2.py
index bc5040cc6..01fc552b9 100644
--- a/project_euler/problem_02/sol2.py
+++ b/project_euler/problem_02/sol2.py
@@ -11,28 +11,28 @@ n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
 """
 
 
-def solution(n):
+def solution(n: int = 4000000) -> int:
     """Returns the sum of all fibonacci sequence even elements that are lower
     or equals to n.
 
     >>> solution(10)
-    [2, 8]
+    10
     >>> solution(15)
-    [2, 8]
+    10
     >>> solution(2)
-    [2]
+    2
     >>> solution(1)
-    []
+    0
     >>> solution(34)
-    [2, 8, 34]
+    44
     """
-    ls = []
+    even_fibs = []
     a, b = 0, 1
     while b <= n:
         if b % 2 == 0:
-            ls.append(b)
+            even_fibs.append(b)
         a, b = b, a + b
-    return ls
+    return sum(even_fibs)
 
 
 if __name__ == "__main__":
diff --git a/project_euler/problem_02/sol3.py b/project_euler/problem_02/sol3.py
index f29f21c28..53d8ca6f1 100644
--- a/project_euler/problem_02/sol3.py
+++ b/project_euler/problem_02/sol3.py
@@ -11,7 +11,7 @@ n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
 """
 
 
-def solution(n):
+def solution(n: int = 4000000) -> int:
     """Returns the sum of all fibonacci sequence even elements that are lower
     or equals to n.
 
diff --git a/project_euler/problem_02/sol4.py b/project_euler/problem_02/sol4.py
index be4328941..a87410b70 100644
--- a/project_euler/problem_02/sol4.py
+++ b/project_euler/problem_02/sol4.py
@@ -13,7 +13,7 @@ import math
 from decimal import Decimal, getcontext
 
 
-def solution(n):
+def solution(n: int = 4000000) -> int:
     """Returns the sum of all fibonacci sequence even elements that are lower
     or equals to n.
 
@@ -57,8 +57,8 @@ def solution(n):
 
     index = (math.floor(math.log(n * (phi + 2), phi) - 1) // 3) * 3 + 2
     num = Decimal(round(phi ** Decimal(index + 1))) / (phi + 2)
-    sum = num // 2
-    return int(sum)
+    total = num // 2
+    return int(total)
 
 
 if __name__ == "__main__":
diff --git a/project_euler/problem_02/sol5.py b/project_euler/problem_02/sol5.py
index 180906cf8..dcf6eae85 100644
--- a/project_euler/problem_02/sol5.py
+++ b/project_euler/problem_02/sol5.py
@@ -11,7 +11,7 @@ n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
 """
 
 
-def solution(n):
+def solution(n: int = 4000000) -> int:
     """Returns the sum of all fibonacci sequence even elements that are lower
     or equals to n.
 
@@ -27,19 +27,19 @@ def solution(n):
     44
     """
 
-    a = [0, 1]
+    fib = [0, 1]
     i = 0
-    while a[i] <= n:
-        a.append(a[i] + a[i + 1])
-        if a[i + 2] > n:
+    while fib[i] <= n:
+        fib.append(fib[i] + fib[i + 1])
+        if fib[i + 2] > n:
             break
         i += 1
-    sum = 0
-    for j in range(len(a) - 1):
-        if a[j] % 2 == 0:
-            sum += a[j]
+    total = 0
+    for j in range(len(fib) - 1):
+        if fib[j] % 2 == 0:
+            total += fib[j]
 
-    return sum
+    return total
 
 
 if __name__ == "__main__":