## Inscribed Squares

Above are two identical isosceles right triangles containing two inscribed squares. In one, a perfect square has been inscribed such that two sides line up with the two legs of the right triangle. In the other, a perfect square has…

## Compound Word Puzzle 2

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 to each of them?

## Compound Word Puzzle 1

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 to each of them?

## Reverse the Digits and Add

I am thinking of a 3-digit number. When you reverse the digits of this number, you get a bigger number, and if you add that to the original number, the sum is 463. What was the number I was thinking…

## Card Flipping Endgame

There are n playing cards lined up face-down in a row. Every turn, a pair of adjacent cards with the left card face-down is randomly selected (i.e., a pair of cards has no chance of being selected if the left…

## Drink Mix Riddle

Two kids are playing around with their drinks at lunch. One has 200ml of milk and the other has 200ml of chocolate milk. They scoop 20ml of chocolate milk into the milk glass, then they scoop 20ml of whatever is…

## Number Deduction

A teacher gives three clever students in her class a challenge: she writes down 3 different numbers on 3 index cards, and has each student hold up one of the cards to their forehead such that they can’t see their…

## Matchstick Math 1

Move exactly 1 match to make this a valid equation. Bonus: find two different ways to solve this. In matchstick math puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That…

## Calculator Error Riddle

A kid is adding consecutive integers on a calculator, one at a time, starting with 1 + 2 + 3 + … and so on. At one point you notice the sum is now 100, but that shouldn’t be possible…

## Tricky, Tricky

Can you figure out the number I am thinking of? Some cryptic clues: If you have all the answers right, that’s only about 33% percent of the solution: you need to justify them too. Some clues were left over, so…

## Unique Number of Letters

Out of all whole numbers between one and five thousand, there is only one number that has a unique number of letters when you spell it out. What number is it? Include spaces and dashes. For example, “twenty-four” and “two…

## How Many Daughters

A mother randomly selected two of her children to pick up a package from the post office. There was a 50% chance both children were daughters. How many daughters does this mother most likely have?

## Battery Test Puzzle

You have four good/new batteries and four bad/used batteries but don’t know which are which. You have a flashlight that uses two batteries, which will only work if both batteries are good – if it doesn’t work, you won’t know…

## Ultimate Guide to Brain Teaser Interview Questions

1. Why Brain Teasers To understand how to tackle brain teasers at an interview, first understand what brain teasers are and why they are used. What Are Brain Teasers Brain teasers can be thought of broadly as types of puzzles…

## Chess Tactic Puzzle

Black is down significant material, but has a strong series of moves to turn things around. Can you find it?

## Food with 5 Letters

I am a food with 5 letters. Take away my first letter, and I become a form of energy. Take away my first two letters, and I become something you need to live. Rearrange my last three letters, and I…

## Fake Coins Proof

You are a rare coins expert and have determined there are 7 fake coins out of 14 gold coins. Now you need to prove to the judge which ones are fake. It is known that that real coins all weigh…