Can You Solve These 40 Mind-Bending Brain Teasers That Stump Even the Smartest?
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Two trains are 100 miles apart and traveling toward each other. Each travels at 50 miles per hour. A fly travels between them at 75 miles per hour, turning around each time it reaches a train. How far does the fly travel before the trains collide?
Answer: 75 miles. The trains collide after one hour, and the fly travels 75 miles per hour for that hour.
40. The Hotel Rooms
A hotel has 10 floors. Each floor has 10 rooms. How many rooms contain the number 7 in their room number?
Answer: 19. Assuming the rooms are numbered 1 through 100, the digit 7 appears 10 times in the ones place and 10 times in the tens place. Room 77 contains two 7s, so it is counted twice when counting appearances. Therefore, there are 19 rooms containing a 7.
How many brain teasers did you manage to crack on your first try? Whether you breezed through the number patterns or got completely stumped by the river crossing, you can take comfort in knowing your central nervous system got a proper recalibration in the process.
If your brain isn’t completely fried, pass these along to your friends, family, or coworkers to see who claims the title of ultimate puzzle master. Then circle back to the Mental Floss quiz page for even more riddles, trivia, and mind-bending challenges.
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