diff --git a/2025/ruby/day_03.rb b/2025/ruby/day_03.rb
new file mode 100644
index 0000000..374329f
--- /dev/null
+++ b/2025/ruby/day_03.rb
@@ -0,0 +1,10 @@
+banks = DATA.read.lines(chomp: true)
+  .map { it.chars.map(&:to_i) }
+
+pp banks.map {|bank|
+  a = bank[0..-2].max
+  i = bank.index(a)
+  [a, bank[i+1..].max].join.to_i
+}.sum
+
+__END__