13 brain teasers with answers (logic, numbers, words and riddles)
· 5 min read
Here are thirteen brain teasers for adults — logic puzzles, number puzzles, word puzzles and a couple of riddles — each with its answer and a short explanation hidden underneath. Try each one properly before you open the answer; the pleasure of a good teaser is almost entirely in the moment it clicks.
How to get the most out of a brain teaser
Most brain teasers work by nudging you towards an obvious answer that turns out to be wrong. A few habits help:
- Distrust your first answer. If it arrived instantly, check it against the question once more.
- Read every word. Teasers are written carefully, and the key detail is often a single word you skimmed over.
- Write it down. Numbers and family relationships are much easier on paper than in your head.
- Give it a minute. If you are stuck, move on and come back. A fresh look solves a surprising number of these.
Logic teasers
1. The bat and the ball
A bat and a ball cost £1.10 together. The bat costs exactly £1.00 more than the ball. How much does the ball cost?
Answer
5p. The tempting answer is 10p, but then the bat would be £1.10 and the pair would cost £1.20. If the ball is 5p, the bat is £1.05, and together they make £1.10.
2. The fishing trip
Two fathers and two sons go fishing. They catch exactly three fish, and each of them takes home one whole fish. How is that possible?
Answer
There are only three people: a grandfather, his son and his grandson. The grandfather and the middle man are both fathers; the middle man and the youngest are both sons.
3. Socks in the dark
A drawer holds ten black socks and ten white socks, all mixed up. The light is broken. What is the smallest number of socks you must take out to be certain of having a matching pair?
Answer
Three. With only two colours, the first two socks might differ, but the third must match one of them.
4. The portrait
A man looks at a portrait and says: “I have no brothers or sisters, but this man’s father is my father’s son.” Who is in the portrait?
Answer
His son. With no brothers, “my father’s son” can only be the speaker himself. So the sentence becomes “this man’s father is me”.
Number teasers
5. The lily pads
A patch of lily pads on a pond doubles in size every day. It takes 48 days to cover the whole pond. On which day was the pond half covered?
Answer
Day 47. Because the patch doubles daily, it was half the size the day before it filled the pond. The instinct to say day 24 treats doubling as if it were steady growth.
6. The machines
Five machines take five minutes to make five widgets. How long would 100 machines take to make 100 widgets?
Answer
Five minutes. Each machine makes one widget in five minutes. A hundred machines working side by side make a hundred widgets in the same five minutes.
7. The striking clock
A clock takes five seconds to strike six o’clock, timed from the first chime to the last. At the same pace, how long does it take to strike twelve?
Answer
Eleven seconds. Six chimes have five gaps between them, so each gap is one second. Twelve chimes have eleven gaps.
8. What comes next?
1, 11, 21, 1211, 111221, …
Answer
312211. Each term describes the one before it out loud. “1” is one 1, so 11. That is two 1s, so 21. Then one 2, one 1: 1211. And so on: 111221 is three 1s, two 2s, one 1, giving 312211.
Word teasers
9. Shorter by growing
Which word gets shorter when you add two letters to it?
Answer
Short. Add “er” and it becomes “shorter”.
10. Keep it down
Rearrange the letters of LISTEN to make a word that means making no sound.
Answer
Silent. The same six letters also make “enlist”, “tinsel” and “inlets”, but only one of them means quiet.
11. The letter sequence
What letter comes next: J, F, M, A, M, J, J, …?
Answer
A. They are the first letters of the months: January to July, so August is next.
Classic riddles
12. The busy cloth
The harder I work at drying, the wetter I become. What am I?
Answer
A towel.
13. Neck but no head
I have a neck but no head, I wear a cap, and I am often full of something to drink. What am I?
Answer
A bottle.
What these teasers have in common
Look back and you will notice most of them use one of a small handful of tricks:
- A misleading shortcut. The bat and ball, the lily pads and the machines all invite a quick calculation that feels right and is not.
- Hidden overlap. The fishing trip and the portrait rely on one person filling two roles.
- Counting the wrong thing. The clock is about gaps, not chimes — the same idea as fence posts and fence panels.
- A different kind of pattern. The number and letter sequences are not arithmetic at all; they are descriptions.
Knowing the tricks does not spoil future teasers. It just gives you a short checklist to run through when an answer seems too easy.
If you enjoyed these
Brain teasers are one-off puzzles: once you know the answer, it is spent. If you like the feeling of an idea clicking into place and want something fresh every day, puzzle games are the natural next step.
- Quartets is the closest to a word teaser: sixteen words, four hidden connections, and at least one word that looks as if it belongs somewhere it does not.
- Minesweeper and Sudoku scratch the logic itch, with every board solvable by reasoning alone.
- The daily word is a small deduction puzzle with a definition at the end.
For more in this vein, try our round-up of logic games that make you think.
Play them now
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- QuartetsWordSixteen words hiding four groups of fourPlay4 min · dailyPlay Quartets on BrainBreak. Find the four hidden connections among sixteen words. The obvious grouping is usually the trap.
- MinesweeperLogicRead the numbers, find the mines, never guessPlay5 minPlay Minesweeper on BrainBreak. Deduce where the mines are from the numbers around them. Every board here is solvable by reasoning alone.
- SudokuLogicNine by nine, one of each, no guessing requiredPlay10 min · dailyPlay Sudoku on BrainBreak. The classic number-placement puzzle, in four difficulties, with pencil marks and a daily grid everyone gets the same.
- Daily wordWordOne five-letter word a day — and what it means afterwardsPlay3 min · dailyPlay Daily word on BrainBreak. Six guesses at a hidden five-letter word, with a definition and an example sentence waiting at the end of it.