Create luhn_check.py

Author: rkstudio585

luhn_check.py

@@ -0,0 +1,23 @@
+def luhn_check(card_number):
+    card_number = [int(digit) for digit in str(card_number)]
+    checksum = 0
+    
+    # Process each digit from right to left
+    for i in range(len(card_number) - 1, -1, -1):
+        digit = card_number[i]
+        
+        # Double every second digit
+        if (len(card_number) - i) % 2 == 0:
+            digit *= 2
+            # If doubling makes the digit > 9, subtract 9
+            if digit > 9:
+                digit -= 9
+        
+        # Add the processed digit to checksum
+        checksum += digit
+    
+    # Check if the checksum is a multiple of 10
+    return checksum % 10 == 0
+
+# Test the function with an example card number
+print(luhn_check(4539148803436467))  # Output: False (invalid)