diff --git a/ruby_algo/ex4.rb b/ruby_algo/ex4.rb
new file mode 100644
index 0000000..1db4984
--- /dev/null
+++ b/ruby_algo/ex4.rb
@@ -0,0 +1,24 @@
+# A palindromic number reads the same both ways. The largest palindrome made from the 
+# product of two 2-digit numbers is 9009 = 91 × 99.
+
+# Find the largest palindrome made from the product of two 3-digit numbers.
+
+x = 0 
+b = 100
+y = []
+
+while b < 1000
+  a = 100
+  while a < 1000
+    x = a * b
+    x = x.to_s
+    if x == x.reverse
+      y << x.to_i
+    end
+    a += 1
+  end
+  b += 1
+end
+
+puts y.sort.max
+