diff --git a/.gitignore b/.gitignore
index 69ab9db4..8d2b460b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,5 @@
 /checkouts
 /.lein-deps-sum
 /.lein-plugins
+.lein-repl-history
+.nrepl-port
diff --git a/src/training_day.clj b/src/training_day.clj
index f5ac2e69..c3ddeee5 100644
--- a/src/training_day.clj
+++ b/src/training_day.clj
@@ -1,11 +1,18 @@
 (ns training-day)
 
-(def answer ":(")
+(def answer 42)
 
 (def hai "O HAI!")
 
 (defn square [x]
-  ":(")
+  (* x x))
 
 (defn average [a b]
-  ":(")
+  (/ (+ a b) 2))
+
+(defn           ; Start a function definition:
+  hello         ; name
+  "Gives out personalized greetings." ; a optional docstring
+  [who]                               ; parameters inside brackets
+  (str "Hello, " who "!"))            ; body
+