1. What has keys, but no locks; space, but no room; you can enter, but not go in?
Answer: A keyboard
Solution: A keyboard has keys for typing, space bar, and you can enter data but not physically go in.
2. I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?
Answer: A map
Solution: Maps show cities, mountains, and bodies of water, but not their physical components.
3. I am an odd number. Take away a letter and I become even. What number am I?
Answer: Seven
Solution: "Seven" is an odd number. Remove the 's' and it becomes "even".
4. What breaks yet never falls, and what falls yet never breaks?
Answer: Day breaks and night falls
Solution: This is a play on common phrases about day and night.
5. Forward I am heavy, but backward I am not. What am I?
Answer: The word 'ton'
Solution: 'Ton' is a heavy weight, but spelled backwards it's 'not'.
6. A farmer has 10 trees. On each tree, there are 10 branches. On each branch, there are 10 nests. In each nest, there are 10 eggs. How many trees does the farmer have?
Answer: 10 trees
Solution: The question provides extra information to distract, but only asks about the number of trees.
7. Two fathers and two sons went fishing. They caught three fish and each person got a whole fish. How is this possible?
Answer: There were only three people: a grandfather, his son, and his grandson
Solution: The middle person is both a father and a son.
8. If you have me, you want to share me. If you share me, you haven't got me. What am I?
Answer: A secret
Solution: People want to share secrets, but once shared, it's no longer a secret.
9. You are in a room with three light switches.
Answer: Turn on one switch for a while, then turn it off and turn on another. Enter the room - the warm bulb corresponds to the first switch, the lit bulb to the second, and the cold, unlit bulb to the third.
10. You are in a room with two doors. One door leads to freedom, and the other leads to certain death.
Answer: Ask either guard: "If I were to ask the other guard which door leads to freedom, what would he say?" Then choose the opposite door.
11. You have two ropes. Each rope takes exactly one hour to burn from one end to the other.
Answer: Light both ends of one rope and one end of the other. When the first rope burns out (30 minutes), light the other end of the second rope. It will burn out after another 15 minutes, totaling 45 minutes.
12. Four people need to cross a bridge at night. They have one flashlight, and the bridge is too dangerous to cross without it.
Answer: The fastest way is 17 minutes. The two fastest cross first, then the fastest returns. The two slowest cross, then the second fastest returns. Finally, the two fastest cross again.
13. Three men are wearing hats. Each hat is either red or blue, but none of them knows the color of their own hat.
Answer: All three men are wearing red hats.
14. You have 12 identical-looking coins, but one of them is either heavier or lighter than the others.
Answer: Use the balance scale three times, dividing the coins into groups and comparing weights to isolate the odd coin.
15. A man walks into a room with three doors. Behind one door is a pile of gold, behind another is a lion that hasn't eaten in three days, and behind the third is a trap that will activate as soon as the door is opened.
Answer: Choose the door with the lion.
Solution: A lion that hasn't eaten in three days would be dead, making it the safest choice.
Did you make it into the elite 2% who can solve them all? Share your results in the comments below and challenge your friends to see how they measure up!
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