For each one, first the puzzle is posed for you to solve within a recommended time. A detailed systematic solution then follows.
Matchstick puzzles, riddles, math puzzles, logic puzzles, river crossing puzzles, ball weighing puzzles are some of the categories.
The full list of all brain teasers with solutions is available in the link,
Challenging brain teasers with solutions: Long list.
This will always be the most up-to-date list with the brain teasers classified into categories that can be browsed separately.
Matchstick tower puzzle: Move 4 matches to invert the tower. This is a different type of matchstick puzzle that is challenging to solve in 20 minutes.
9 squares puzzle: Find area of rectangle with 9 gradually smaller squares inside it and the side length of smallest square 3 units. Time 30 minutes.
Surely you can solve the 3 digit number puzzle in 20 mins if you approach the puzzle with systematic problem solving techniques.
Find area of equilateral triangle if side length of smallest of 3 squares inscribed in the triangle on top of each other is 1. It needs a bit of math.
Repetition riddle: What is in 2012th position of PROBLEMSOLVINGPROBLEMSOLVING... continued indefinitely? To solve, don't count, find a rule in repetitions.
You have three wrongly labeled boxes BB, BR, and RR. Each contains colored balls (Blue, Red, or both). Pick a ball from one box to correct the three labels.
Two children differ in ages by 5 years. Sum of squares of the ages is 97. Place squares of the ages one after other forming square of mother's age. Find it.
In liar and truth-teller riddle, to know the safe path, a traveler can ask only one question to any one of a habitual liar or a truth-teller. What to ask?
Bridge Crossing Riddle: 4 persons to cross a bridge at night in 17 mins. They have one torch, walk at different speeds and maximum two can cross together.
The 7 squares matchstick puzzle: Move 2 matches to make 7 squares in the puzzle figure. Time 10 mins. Apply reasoning based on matchstick puzzle concepts.
