some progress

test/ruby/23.out

@@ -0,0 +1,23 @@
+def factorial(n)
+  """Calculate factorial recursively"""
+  if n <= 1
+    return 1
+  else
+    return n * factorial(n - 1)
+  end
+end
+def is_prime(num)
+  if num < 2
+    return false
+  end
+  for i in 2...Integer(num ** 0.5) + 1
+    if num % i == 0
+      return false
+    end
+  end
+  return true
+end
+print("Factorial of 5: #{factorial(5)}", "\n")
+for n in [2, 3, 4, 17, 21]
+  print("#{n} is prime: #{is_prime(n)}", "\n")
+end