diff --git a/11/day11.py b/11/day11.py
new file mode 100644
index 0000000..bd1cecb
--- /dev/null
+++ b/11/day11.py
@@ -0,0 +1,67 @@
+from sys import argv
+from re import finditer
+
+ROUND_COUNT = 10000
+
+class Monkey:
+    monkeys = []
+    def __init__(self, start_items:list[int], divisible_by:int, monkey_on_true: int, monkey_on_false: int, operation: str ):
+        self.items = start_items
+        self.div_by = divisible_by
+        self.monkey_on_true = monkey_on_true
+        self.monkey_on_false = monkey_on_false
+        self.operation = lambda x : x
+        self.inspections = 0
+        if operation.startswith('*'):
+            try:
+                i = int(operation[2:])
+                self.operation = lambda x : x * i
+            except:
+                self.operation = lambda x : x * x
+        else:
+            try:
+                i = int(operation[2:])
+                self.operation = lambda x : x + i
+            except:
+                self.operation = lambda x : x + x
+        Monkey.monkeys.append(self)
+    def do_business(self):
+        for _ in range(len(self.items)):
+            self.items[0] = self.operation(self.items[0])# // 3
+            if self.items[0] % self.div_by == 0:
+                Monkey.monkeys[self.monkey_on_true].recv_item(self.items.pop(0))
+            else:
+                Monkey.monkeys[self.monkey_on_false].recv_item(self.items.pop(0))
+            self.inspections += 1
+
+    def recv_item(self, item: int):
+        self.items.append(item)
+    def get_inspections(self):
+        return self.inspections
+
+re_monkey = r"Monkey (\d+):\n *Starting items: (.*)\n *Operation: new = old (.*)\n *Test: divisible by (\d+)\n *If true: throw to monkey (\d+)\n *If false: throw to monkey (\d+)"
+
+def do_monkey_business(filename):
+    with open(filename, "r") as file:
+        content = file.read()
+    for match in finditer(re_monkey, content):
+        g = match.groups()
+        print(g)
+        Monkey([int(x) for x in g[1].replace(" ", "").split(",")], int(g[3]), int(g[4]), int(g[5]), g[2])
+
+    for r in range(ROUND_COUNT):
+        print(f"Round {r}")
+        for i in range(len(Monkey.monkeys)):
+            Monkey.monkeys[i].do_business()
+
+    ranking = [m.get_inspections() for m in Monkey.monkeys]
+    ranking.sort()
+    result = ranking[-2] * ranking[-1]
+    print(ranking)
+    print(f"Monkey business level at {result}")
+
+if __name__ == '__main__':
+    if not len(argv) == 2:
+        print(f"Expected exactly one argument (filename), got {len(argv)-1}")
+        exit(1)
+    do_monkey_business(argv[1])
diff --git a/11/monkey-stuff.txt b/11/monkey-stuff.txt
new file mode 100644
index 0000000..c567cb6
--- /dev/null
+++ b/11/monkey-stuff.txt
@@ -0,0 +1,55 @@
+Monkey 0:
+  Starting items: 62, 92, 50, 63, 62, 93, 73, 50
+  Operation: new = old * 7
+  Test: divisible by 2
+    If true: throw to monkey 7
+    If false: throw to monkey 1
+
+Monkey 1:
+  Starting items: 51, 97, 74, 84, 99
+  Operation: new = old + 3
+  Test: divisible by 7
+    If true: throw to monkey 2
+    If false: throw to monkey 4
+
+Monkey 2:
+  Starting items: 98, 86, 62, 76, 51, 81, 95
+  Operation: new = old + 4
+  Test: divisible by 13
+    If true: throw to monkey 5
+    If false: throw to monkey 4
+
+Monkey 3:
+  Starting items: 53, 95, 50, 85, 83, 72
+  Operation: new = old + 5
+  Test: divisible by 19
+    If true: throw to monkey 6
+    If false: throw to monkey 0
+
+Monkey 4:
+  Starting items: 59, 60, 63, 71
+  Operation: new = old * 5
+  Test: divisible by 11
+    If true: throw to monkey 5
+    If false: throw to monkey 3
+
+Monkey 5:
+  Starting items: 92, 65
+  Operation: new = old * old
+  Test: divisible by 5
+    If true: throw to monkey 6
+    If false: throw to monkey 3
+
+Monkey 6:
+  Starting items: 78
+  Operation: new = old + 8
+  Test: divisible by 3
+    If true: throw to monkey 0
+    If false: throw to monkey 7
+
+Monkey 7:
+  Starting items: 84, 93, 54
+  Operation: new = old + 1
+  Test: divisible by 17
+    If true: throw to monkey 2
+    If false: throw to monkey 1