diff --git a/easy/watter_bottles.py b/easy/watter_bottles.py
new file mode 100644
index 0000000..def1e27
--- /dev/null
+++ b/easy/watter_bottles.py
@@ -0,0 +1,10 @@
+# https://leetcode.com/problems/water-bottles
+class Solution:
+    def numWaterBottles(self, numBottles: int, numExchange: int) -> int:
+        ret = numBottles
+        while numBottles >= numExchange:
+            full = numBottles // numExchange
+            ret += full
+            numBottles = (numBottles % numExchange) + full
+        return ret
+