diff --git a/src/advent/util.cr b/src/advent/util.cr
index bd82cfb..00acd6b 100644
--- a/src/advent/util.cr
+++ b/src/advent/util.cr
@@ -48,6 +48,12 @@ struct Tuple(*T)
     return self if gcd == 0
     { self[0]//gcd, self[1]//gcd}
   end
+
+  def signum
+    {% begin %}
+      { {% for t, i in T %} self[{{i}}].signum, {% end %} }
+    {% end %}
+  end
 end
 
 struct Number