Brain teasers
Sixteen logic puzzles, riddles, and number traps from Think Fanny. Solve first, then tap reveal answer on each page for the short why behind it. Want a weekly rhythm instead of a single shot? Pair this library with the logic practice guide.
Every answer here is re-solved from a cold start before the page goes live: how puzzles and answers are checked.
Start here by difficulty
Three teasers that show how the library reads. One easy, one medium, one hard.
What has a neck but no head?
A clean one-liner riddle with a concrete answer.
Fox, goose, and grain
Get a fox, a goose, and a sack of grain across the river without anyone eating lunch early.
Prisoners in a line with hats
They hear one letter, then each must guess. How do they save almost everyone?
Logic teasers
Deduction-first puzzles where one honest clue unpacks the rest.
Three switches, one bulb
A classic room puzzle with three switches and one light. Find the method that always works.
Fox, goose, and grain
Get a fox, a goose, and a sack of grain across the river without anyone eating lunch early.
Blue eyes, brown eyes, and a ferry
A famous induction puzzle. Why does the guru's sentence start a countdown?
Nine balls, one heavy, two weighings
Find the heavy ball with a balance scale and only two uses.
Three wise people, red hats
They can see others' hats. Who figures out their color, and how?
Prisoners in a line with hats
They hear one letter, then each must guess. How do they save almost everyone?
Riddle teasers
Short prompts with a concrete payoff. Read carefully, answer fast.
Two coins add up to 30 cents
A short money riddle that trips people who assume both coins are normal.
What has a neck but no head?
A clean one-liner riddle with a concrete answer.
The man who only rides to floor 10
A short man takes the elevator. Why does his routine change on rainy days?
What is always in front of you but cannot be seen?
A one-line riddle for a quick win.
Numbers teasers
Math-adjacent traps that fold once you spot the framing trick.
Odd one out: 3, 5, 7, 9, 11, 13
One number does not belong with the primes in this short list.
When are clock hands at right angles?
How many times do the hour and minute hands form a right angle between noon and midnight?
The missing dollar
Three guests, a hotel refund, and a story that does not add up. Where is the flaw?
Split $47 three ways
A mental-math money split with a one-cent catch.
Words teasers
Language puzzles that reward a slow second read.
Visual teasers
Matchsticks, shapes, and geometry you can picture or draw out.
How these teasers work
Each teaser page prints the puzzle up top, with no answer visible above the fold. Work it in your head or on paper, then tap reveal answer to check. The explanation underneath is short on purpose, just enough to show the method so the next puzzle in the same family gets easier.
Stuck on a category? The practice guide breaks down how to drill one pattern family at a time, from balance-scale splits to hat-problem parity codes.