IKMC 2027 - Grades 5-6 - Self-study SET 3 - Thematic Batch 3 Question 7

Tom has four cards bearing 1, 3, 6, 7. How many four-digit numbers can he arrange using the cards?



Editorial clarification for the intended source answer: The 6 card may be turned upside down to show 9. Without this convention the answer is 24.