diff --git a/src/day7.clj b/src/day7.clj
new file mode 100644
index 0000000..e00943b
--- /dev/null
+++ b/src/day7.clj
@@ -0,0 +1,75 @@
+(ns day7
+  (:require [clojure.string :as string]
+            [helpers :refer [get-input]]))
+
+(def example
+"190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20")
+
+(def input
+  (->>
+   ;example
+   (get-input 7)
+   string/split-lines))
+
+(defn permutation->operator [p]
+  (concat
+   (map #(if (even? %) + *) p)
+   (map #(if (odd? %) + *) p)))
+
+(defn operators [n]
+  (let [add-operators
+        (fn [ops]
+          (vector (conj ops +)
+                  (conj ops *)))]
+    (loop [i 1 ops [[+] [*]]]
+      (if (= n i)
+        ops
+        (recur (inc i)
+               (mapcat add-operators ops))))))
+
+(defn test-calibration [ops-fn s]
+  (let [[tval ns] (string/split s #":")
+        tval (parse-long tval)
+        ns (vec (map parse-long
+                     (-> ns string/trim (string/split #" "))))
+        ops (-> ns count dec ops-fn)
+        check-fn
+        (fn [op-seq]
+          (reduce
+           (fn [r i]
+             ((get op-seq i) r (get ns (inc i))))
+           (first ns)
+           (range (count op-seq))))]
+    (if (empty?
+         (filter (partial = tval) (map check-fn ops)))
+      0 tval)))
+
+(println "Total calibration result:"
+         (reduce + (map (partial test-calibration operators) input)))
+
+
+(defn || [a b]
+  (parse-long (str a b)))
+
+(defn operators2 [n]
+  (let [add-operators
+        (fn [ops]
+          (vector (conj ops +)
+                  (conj ops *)
+                  (conj ops ||)))]
+    (loop [i 1 ops [[+] [*] [||]]]
+      (if (= n i)
+        ops
+        (recur (inc i)
+               (mapcat add-operators ops))))))
+
+(println "Total calibration result (part 2):"
+         (reduce + (map (partial test-calibration operators2) input)))