diff --git a/0504_base-7/README.md b/0504_base-7/README.md
new file mode 100644
index 0000000..76f2897
--- /dev/null
+++ b/0504_base-7/README.md
@@ -0,0 +1,17 @@
+Given an integer `num`, return _a string of its **base 7** representation_.
+
+**Example 1:**
+
+    Input: num = 100
+    Output: "202"
+    
+
+**Example 2:**
+
+    Input: num = -7
+    Output: "-10"
+    
+
+**Constraints:**
+
+*   `-107 <= num <= 107`
\ No newline at end of file
diff --git a/0504_base-7/python3/solution.py b/0504_base-7/python3/solution.py
new file mode 100644
index 0000000..7f4ed76
--- /dev/null
+++ b/0504_base-7/python3/solution.py
@@ -0,0 +1,11 @@
+class Solution:
+    def convertToBase7(self, num: int) -> str:
+        sign = '-' if num < 0 else ''
+        num = abs(num)
+        b7 = ''
+        
+        while num > 0:
+            b7 = str(num % 7) + b7
+            num //= 7
+        
+        return '0' if b7 == '' else sign + b7