100+ Brainteasers with answers for kids and adults

Brainteasers with Answers - "Challenge your brain and improve your problem-solving skills with our collection of brainteasers. From logic puzzles to wordplay, our brainteasers will keep you entertained and engaged for hours. Whether you're a student looking to boost your grades or an adult looking to keep your mind sharp, our brainteasers have something for everyone. Test your mental aptitude and see just how clever you are with our challenging and fun collection of brainteasers."

Three friends check into a hotel room that costs $30. They each contribute $10 and pay the bill. Later, the hotel realizes they made a mistake and the room only costs $25. The bellboy is sent to return $5 to the friends. Unsure how to split the $5, the bellboy decides to give each friend $1 and keep $2 as a tip. Now, each friend has paid $9 (totaling $27), and the bellboy kept $2, which sums up to $29. Where is the missing dollar?

Show Answer

There is no missing dollar. The mistake lies in the way the total is calculated. The $27 already includes the $2 that the bellboy took. So, $25 went to the hotel, and $2 went to the bellboy.

You have a fox, a chicken, and a sack of grain. You need to get all three across a river using a boat that can only carry one at a time. If you leave the fox with the chicken, the fox will eat the chicken. If you leave the chicken with the grain, the chicken will eat the grain. How can you get all three across the river safely?

Show Answer

1. Take the chicken across the river.
2. Go back and take the fox across the river.
3. Take the chicken back to the original side.
4. Take the grain across the river.
5. Finally, go back and bring the chicken across.

You are in a room with three light switches. Each switch controls one of the three light bulbs in the next room. You can flip the switches as many times as you like, but you can only go into the next room once. How do you determine which switch controls which bulb?

Show Answer

Turn on the first switch and leave it on for a few minutes.
2. Turn it off and immediately turn on the second switch.
3. Go into the next room:
- The bulb that is on is controlled by the second switch.
- The bulb that is warm but off is controlled by the first switch.
- The bulb that is cold and off is controlled by the third switch.

You have two hourglasses: one measures 7 minutes and the other measures 4 minutes. How can you measure exactly 9 minutes?

Show Answer

1. Start both hourglasses at the same time.
2. When the 4-minute hourglass runs out, flip it immediately.
3. When the 7-minute hourglass runs out, flip it immediately.
4. When the 4-minute hourglass runs out again (at 8 minutes), there is 1 minute of sand left in the 7-minute hourglass.
5. Let that 1 minute pass. You're now measured exactly 9 minutes.

You are standing in front of two doors. One leads to freedom, and the other leads to death. Two guards are standing, one in front of each door. One always tells the truth, and the other always lies, but you don't know which one is which. You can ask only one question to one of the guards to figure out which door leads to freedom. What do you ask?

Show Answer

Ask either guard, "If I were to ask the other guard which door leads to freedom, what would they say?" Then, choose the opposite door.

You have three switches outside a room. Each switch controls one of the three bulbs inside the room. All the switches are in the "off" position, and you can't see the bulbs from the outside. How can you figure out which switch controls which bulb if you can only enter the room once?

Show Answer

1. Turn on the first switch and leave it on for a few minutes.
2. Turn it off and immediately turn on the second switch.
3. Enter the room:
- The bulb that is on is controlled by the second switch.
- The bulb that is warm but off is controlled by the first switch.
- The bulb that is cold and off is controlled by the third switch.

Manhole covers are round so they can fall through the opening. A round cover cannot be turned sideways and dropped through its circular opening, unlike square or rectangular covers.

You have 12 identical-looking balls, but one is of a different weight (heavier or lighter). You have a balance scale and can only use it three times. How do you find the odd ball?

Show Answer

1. Divide the balls into three groups of four.
2. Weigh two of the groups against each other:
- If they balance, the odd ball is in the third group.
- If they don? balance, the odd ball is in the heavier or lighter group.
3. Take the group with the odd ball and divide it into three. Repeat the weighing process.

You have a 5-liter jug and a 3-liter jug. Neither has any markings on it. How can you measure exactly 4 liters using these jugs?

Show Answer

1. Fill the 5-liter jug to the top.
2. Pour water from the 5-liter jug into the 3-liter jug until it is full. This leaves you with 2 liters in the 5-liter jug.
3. Empty the 3-liter jug and pour the 2 liters from the 5-liter jug into the 3-liter jug.
4. Fill the 5-liter jug again and pour it into the 3-liter jug until it is full. Now you have exactly 4 liters left in the 5-liter jug.

Two parallel mirrors are facing each other, and a candle is placed between them. How many images of the candle will you see?

Show Answer

You will see an infinite number of images. Each mirror reflects the candle and the reflection from the other mirror, creating an endless series of reflections.

A woman stole a necklace and put it in her pocket. However, the next day she found the necklace was gone, yet her pocket was not torn or broken, and nothing else was taken. How is this possible?

Show Answer

The woman was a dreamer and dreamed about stealing the necklace. When she woke up, the necklace wasn't there because it never existed in reality.

You have 7 apples. You need to distribute them among 7 people in such a way that each person gets 1 apple, but one apple must remain in the basket. How do you do it?

Show Answer

Give 1 apple to each of the first 6 people, and give the 7th apple along with the basket to the last person. This way, everyone gets an apple, and one apple remains in the basket.

The egg. Evolutionarily, the first egg that contained the genetic mutation to become a chicken was laid by a bird that was not quite a chicken, making the egg the precursor.

A train 1 mile long is traveling at a speed of 1 mile per minute through a tunnel 1 mile long. How long will it take for the train to completely pass through the tunnel?

Show Answer

It will take 2 minutes. The front of the train takes 1 minute to exit the tunnel, but the back still needs another minute to completely pass through.