Multiple choice

How many times are the hands of a clock in a straight line in 84 hours? (Starting from 00:00)

  1. 44

  2. 154

  3. 77

  4. 86
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Clock hands are in a straight line 11 times every 12 hours (once every hour except at 11, which overlaps with 12). This includes both overlaps (0 minutes apart) and oppositions (180 degrees apart). In 84 hours, which is 84/12 = 7 complete 12-hour cycles, the hands align 7 × 11 = 77 times. Additionally, since 84 starts from 00:00 (midnight), we count the starting position as the 1st occurrence, giving us 77 + 77 = 154 total straight line positions.

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