Brain Teasers and Puzzles

Difficulty - Very Easy, Rebus

8 Easy Rebus Puzzles for Kids

A rebus is a puzzle in which words, objects, or symbols are arranged in a way to indirectly represent a commonly known word or phrase. Solving rebus puzzles can be a fun and easy way for kids to think both creatively and analytically.

Here are 8 easy rebus puzzles for kids to get started:

Rebus 1

HANDED

Click for Solution to Rebus 1

Red handed
(“Handed” is written in red text)

Chess, Difficulty - Easy

Mate in 2 Chess Puzzle 3

White to play and mate in 2.

Difficulty - Easy, Geometry

Maximize Triangle Area

If a triangle has two sides with lengths 3 and 4, what should the length of the third side be in order to maximize the area of the triangle?

Difficulty - Easy, Word Puzzles

Compound Word Puzzle 3

Compound words are words that are composed of two or more other words, like high + light = highlight.

Can you make compound words out of the following three words by adding the same 4-letter word either before or after each word?

CROSS
WORKS
WILD

View Solution

Difficulty - Medium, Number Theory

Multiple of 24

Prove that for all prime numbers p > 3, (p² – 1) is a multiple of 24.

Difficulty - Easy, Simple Math

Most Frequent Digit

What is the most frequent digit among the numbers between 1 and 1000 (inclusive)? Consider only base-10 whole numbers.

Difficulty - Medium, Interview Brain Teasers, Probability

Same Birthday in Line

There is a long line of people waiting to see a new movie. They announce that the first person to have the same birthday as someone standing before them in the line gets to meet one of the actors in the movie.

What place in line would maximize your chances of winning? Assume birthdays are uniformly distributed through the year.

Difficulty - Hard, Interview Brain Teasers, Logic Puzzles

Prison Keys Strategy

A prison warden was feeling capricious and played a game with the prison keys:

Each prisoner is handed a key to another prisoner’s cell.
Each prisoner will know which other prisoner was initially given the key to their cell (but does not know whose key they were handed).
Each day, when all prisoners are out of their cells and no one is watching, each prisoner is allowed to place keys in another prisoner’s cell.
Each night, each prisoner can collect any keys placed in their cell.
The prisoners can summon the warden when they’re sure everyone has their own key – but if they are wrong, they’re immediately executed.
The prisoners can discuss a strategy beforehand but cannot communicate in any way after keys are handed out.

What is the fewest number of days it would take for the prisoners to be sure everyone has their key? What was the strategy to achieve this?

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Difficulty - Medium, Number Theory

Digital Sum of the Sum

The digital sum of a number is just the sum of the individual digits. E.g., the digital sum of 123 is 1 + 2 + 3 = 6.

The digital sum of x is 42
The digital sum of y is 67
When x and y are added, you have to “carry the 1” exactly five times (e.g., if you add 8 and 9, you “carry the 1” once to get a “1” in the tens digit, thereby getting 17)

What is the digital sum of z = x + y?

Difficulty - Very Easy, Riddles and Lateral Thinking

If you share me you haven’t got me

If you have me, you want to share me. If you share me, you haven’t got me. What am I?

Click to show solution to “If you share me you haven’t got me”

A secret

Many people who have a secret want to share it. But if you share a secret, it is no longer secret, so you haven’t got it anymore.