diff --git a/test/ruby/23.in b/test/ruby/23.in
new file mode 100644
index 0000000..33b2afc
--- /dev/null
+++ b/test/ruby/23.in
@@ -0,0 +1,21 @@
+# test_basic.py
+def factorial(n):
+    """Calculate factorial recursively"""
+    if n <= 1:
+        return 1
+    else:
+        return n * factorial(n - 1)
+
+def is_prime(num):
+    if num < 2:
+        return False
+    for i in range(2, int(num ** 0.5) + 1):
+        if num % i == 0:
+            return False
+    return True
+
+# Test the functions
+print(f"Factorial of 5: {factorial(5)}")
+
+for n in [2, 3, 4, 17, 21]:
+    print(f"{n} is prime: {is_prime(n)}")
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