During the motion of the hour and minute hand from 1:00 pm to 10:00 pm, how many times do they form a right angle?
Q1. During the motion of the hour and minute hand from 1:00 pm to 10:00 pm, how many times do they form a right angle?
Answer: 18
Explanation: In each hour the hands form a right angle exactly twice, so in 9 hours (1 pm to 10 pm) they form 9 × 2 = 18 right angles.