[Brain Training] Difficult Riddles That Even Adults Struggle With
Everyone played riddles when they were little, right?
But I bet many people don’t do them much anymore as adults.
So I’ve put together some tricky riddles that even grown-ups will find challenging—perfect for you.
Take a quick look; trying them again after a long time might feel surprisingly fresh.
They’re great for killing time while you’re waiting for something or riding the train to work or school!
They’re a good stretch for your brain, so give them a try while reminiscing about the old days.
- [Challenging and Fun!] Quizzes & Riddles for Adults
- [Trick Quiz] Quiz Questions That Excite Everyone from Kids to Adults
- [Battle of Wits] Stimulate your intellectual curiosity! Quiz questions that get adults excited
- A collection of challenging quizzes for adults [Difficult]
- A math quiz for adults. Can you solve it?
- Genius if you can solve it? Super-difficult Quiz Collection
- Mental Workout: Casual Challenge! Riddles for Adults
- [Interesting] Compilation of Trivia Quiz Questions
- [Advanced Level] Difficult Riddles for Elementary School Students
- [Satisfying When Solved] Challenging Quizzes Recommended for Elementary School Students!
- Fun Quiz Questions That Will Liven Up the Office [2026]
- [Difficult] A top recommended quiz collection for junior high school students. Casual questions you can enjoy easily.
- [Interesting] Collection of Math Quiz Problems
[Brain Training] Challenging Riddles That Even Adults Struggle With (31–40)
The smarter you are, the harder it is to solve?! “Where did the 100 yen go?” The “Disappearing 100 Yen” brain teaser
Here’s a problem that might fool the smarter you are.
You tackle it based on illustrations and explanations laid out like a story—but it’s tough… There’s an explanation in the second half, so be sure to watch until the end for the details!
Only geniuses can solve this!? A riddle that reveals innate intelligence
There are quite a few rather tricky questions that stand out, but above all, the uniqueness of the answers makes you nod in agreement.
At the same time, it’s interesting how some answers seem to come from a rather cool, detached perspective.
There are so many fun questions that you might be satisfied just by reading the answers.
Caesar Cipher Quiz
This is a quiz that uses the Caesar cipher, which creates a code by shifting letters by a fixed number.
For example, if you shift “WORLD” forward by 3 letters, it becomes “ZRUOG.” Even if a word looks meaningless at first glance, the key point is that you can reveal the original word by shifting back using the same rule.
To decode it, you need careful observation and patience to determine the correct shift amount, but the sense of accomplishment when you grasp the pattern can be addictive.
It’s perfect as brain training for adults, since you can have fun while honing logical thinking.
Once you get used to it, you can also encrypt your favorite words yourself and exchange them with friends, making it a quiz with a wide range of ways to enjoy.
A cipher quiz using mathematical formulas
A cryptic quiz that looks like simple addition but uses completely different logic to reach the answer.
Equations that seem nonsensical—like 3+7=“trauma” or 4+6+2=“sea slug”—hide tricks such as the ordering of letters or words.
It’s recommended to consider the problem from multiple angles, including letter order and wordplay.
Finding the answer tests your ability to think outside the box.
It’s not just about logical reasoning; a feel for language is also required, making it a quiz that gets your whole brain firing—and becomes addictive.
Even though it was taken, everyone’s laughing. I wonder why.
I ended up fighting after my friend and I both tried to take it… It’s something every elementary schooler has probably experienced at least once.
Having something taken from you feels awful and makes you sad, right? So let’s try this puzzle.
Why is everyone smiling even though something was ‘taken’? The first thing to think about when solving this is the meaning of the word ‘taken’ (torareta).
It’s deliberately written in hiragana, so try converting it to kanji and imagining what situation it might describe.
The answer is: because it was a photograph.
[Brain Training] Difficult Riddles That Even Adults Struggle With (41–50)
There are 5 candies. If you lick one, how many are there?
@igosso.youtube♪ Original Song – Igossou [YouTube] – Igossou [YouTube]
It seems like a question that would trip up adults more than children.
When you read the problem statement, you instinctively want to treat it like an arithmetic problem and think, “5 – 1 = 4, so the answer is 4!” But remember, it’s a trick question.
The hint to solving it is that the candy wasn’t given to someone else, nor did it disappear.
If you think about how many candies you have after you lick one, you should arrive at the correct answer.
An elementary school student with a flexible mind might solve it right away!
A quiz that trips up 99% of people
Quizzes that 99% of people get tripped up by are designed to test your thinking skills and concentration.
Try solving the carefully crafted questions by thinking them through.
You won’t get them just by looking—read carefully, think, and be careful not to fall for the traps.
It’s also a good idea to set a time limit when the questions are presented, or discuss them in a group to come up with answers.
Sometimes the obvious answer turns out to be a trick, so approach them carefully.
