15 Challenging Logic Puzzles and Their Answers

Logic puzzles and brain teasers are great because they challenge you to think deeply, yet the answers often require a surprising amount of creativity. These types of puzzles are perfect for parties, events, or just to test your own problem-solving skills. So, if you’ve found your way to this article, you’re likely seeking a mental challenge from one of these 20 logic puzzles. Fortunately, we’ve included the answers to help you out!

1. The Restaurant Tip Puzzle

Puzzle: A meal costs €97. You pay €100, get €3 back, and tip €2. But your spending is confusingly calculated. What’s the real expense?

Answer: You paid €98 – €97 for food and €1 for the tip.

2. The Man in the Elevator Puzzle

Puzzle: A man lives on the 10th floor but only takes the elevator to the 7th and walks up unless it’s raining. Why?

Answer: He’s short and can only reach the 7th-floor button unless he uses an umbrella.

3. The Fish Riddle

Puzzle: A fish’s head is 3 centimeters long. Its tail is the same length as the head plus half the body. The body is as long as the head and tail together. How long is the fish?

Answer: 24 centimeters. The head is 3 cm long, the body is 12 cm long, and the tail is 9 cm long.

4. The Two Rope Puzzle

Puzzle: You have two ropes and a lighter. Each rope takes exactly one hour to burn but doesn’t burn evenly. How do you measure 45 minutes?

Answer: Light both ends of one rope and one end of the other. When the first rope burns out, 30 minutes have passed; then light the second end of the other rope.

5. The Ball Weighing Puzzle

Puzzle: You have 9 balls, all identical except one that’s heavier or lighter. You have a balance scale and can use it twice. How do you find the odd ball?

Answer: Divide the balls into three groups of three. Weigh two groups; if equal, the odd is in the third. Weigh again two balls within that group to identify it. If equal, the lighter ball is the last one remaining.

6. The Poisoned Drink Puzzle

Puzzle: Five glasses are placed in a row. The first three are filled with water, and the last two with poison. By only moving one glass, make it so no two glasses with water are next to each other.

Answer: Pour the water from the second glass into the fourth, then place the empty glass second.

7. The Light Switch Puzzle

Puzzle: You are outside a closed room with three light switches. Only one of them controls a light inside the room. You can flip the switches as much as you want, but you can only enter the room once to check. How do you know which switch controls the light?

Answer: Turn on two switches, then turn one off after a few minutes. Enter the room; if the bulb is on, it’s the first switch. If the bulb is warm, it’s the second. If cold, it’s the third.

8. The Two Door Puzzle

Puzzle: You’re in a room with two doors. One leads to freedom, and the other to doom. Two guards know which door is which. One always tells the truth, the other always lies. You can ask only one question to one guard. What do you ask?

Answer: Ask, “If I asked the other guard which door leads to freedom, what would they say?” Then choose the opposite door.

9. The 2-sided polygon

Puzzle: Can you draw a polygon with 2 sides and 2 angles of 90 degrees?

Answer: Yes, if you draw it on a sphere.

10. The Three Doors Puzzle

Puzzle: You’re on a game show with three doors. Behind one is a car; the others hide goats. You pick a door, and the host (who knows what’s behind each door) opens another door to reveal a goat. Should you switch your choice?

Answer: Yes, you should switch. Switching gives you a 2/3 chance of winning, while staying gives you only a 1/3 chance.

11. The River Crossing Puzzle

Puzzle: A farmer needs to transport a wolf, a goat, and a cabbage across a river. His boat can only carry him and one other item. If left alone, the wolf will eat the goat, and the goat will eat the cabbage. How can he safely transport all three?

Answer: Take the goat across, go back alone, take the wolf, bring the goat back, take the cabbage across, then return for the goat.

12. The Stolen Ring Puzzle

Puzzle: Four people sit around a table, one stole a ring. Each accuses another, and two are lying. Who stole the ring?

Answer: The only one who gets accused by at least two persons (the two honest persons accusing the stealer).

13. The Colorful Socks Puzzle

Puzzle: You have 20 red and 20 blue socks mixed in a drawer. If you must pull two socks at a time in the dark, what’s the minimum number of pulls to ensure a matching pair?

Answer: Three pulls guarantee a matching pair.

14. The Mirror Reflection Puzzle

Puzzle: How can you stand 1 meter away from a mirror and still see the back of your head?

Answer: There’s a mirror in front of you.

15. The Missing Dollar Puzzle

Puzzle: Three friends share a €300 hotel room. They each pay €100, but the hotel manager realizes there was a discount and gives the bellboy €50 to return. The bellboy keeps €20 and gives €10 back to each person, meaning they each paid €270. But 3 x €90 = €270, plus the €20 the bellboy kept, makes €290. Where’s the missing dollar?

Answer: There’s no missing dollar. The math mixes amounts in an invalid way. The €270 already includes the bellboy’s €20.