How many times in a day, are the hands of a clock in straight line but opposite in direction?
The hands of a clock point in opposite directions (in the same straight line, making an angle 180° between them) 11 times in every 12 hours because between 5 and 7 they point in opposite directions at 6 o clock only.
Hence the hands point in the opposite directions 22 times in a day.
This is already given as a formula and its is better to learn the answer by heart as 22 which can save time in competitive exams.(However you should know the theory behind).