diff --git a/day01/solution.rb b/day01/solution.rb
new file mode 100644
index 0000000..ec1b41c
--- /dev/null
+++ b/day01/solution.rb
@@ -0,0 +1,5 @@
+#!/bin/env ruby
+# Sum all numbers in the text file.
+
+# Part 1
+sum = File.readlines('./input').map { |line| line.to_i)}.sum