Explanation:
When both the starting date and ending date are included, the counting begins from 12 March and ends on 18 March. The dates are 12, 13, 14, 15, 16, 17, and 18, which makes 7 days. Date counting questions are useful in office-based exams because assistants often handle files, deadlines, letters, and official records. Such questions test practical administrative calculation and attention to detail, which are important for clerical and assistant-level government posts.