## The Monty Hall Problem Explained

The Monty Hall Problem You are on a game show in which there are three identical doors, one with a car behind it and two with goats behind them. You must pick one door, and you win if that door…

## 7 Matchstick Equation Puzzles

In matchstick puzzles, you are presented with an incorrect equation made using matchsticks, and you must move 1 or more matchsticks to turn it into a valid equation. You must use all of the matches, and you are not allowed…

## Color of the Last Ball

There is a bag with 20 blue balls and 13 red balls. Randomly remove 2 balls from the bag: Repeat this process until there is just 1 ball remaining. What is the color of the last ball?

## 10 Clever Riddles with Answers

Do some creative thinking and try to solve these 10 clever riddles: Riddle #1 What do you usually have to break before you can use it? Riddle #2 What do you need to answer even though it never asks a…

## Matchstick Equation 4

Move exactly 2 matches to make this a valid equation. Bonus: find two different solutions. In matchstick equation puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it…

## 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…

## 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?

## 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?

## Most Frequent Digit

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

## 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…

## Prison Keys Strategy

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

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

## 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?

## Sharing Game Theory Puzzle

In this sharing game theory puzzle, 3 friends take turns taking from a jar of 1000 candies to share. For example, the 1st friend could take 500 candies, then the 2nd friend could take 400, and the 3rd friend would…

## I Am Normally Below You Riddle

I am a 5-letter word. I am normally below you. If you remove my 1st letter, I am normally above you. If you remove my 1st and 2nd letters, I am all around you.

## Rock Paper Scissors Puzzle

A rock paper scissors puzzle: Anya played 10 games of rock paper scissors against Blake Each time there was a winner (no ties) Anya used rock 2 times, paper 2 times, and scissors 6 times, but you don’t know the…

## How Many Friday the 13th in a Year

Some consider Friday the 13th (any Friday that falls on the 13th day of a month) unlucky. In a calendar year, how many Friday the 13th can occur? Find both the minimum and maximum.

## Ferry Boat Problem

Two ferry boats serve the same route on a river, but travel at different speeds. They depart from opposite ends of the river at the same time, meeting at a point 720 yards from the nearest shore. When each boat…

## Converge to an Integer

Given the iterative formula: xn+1 = sqrt(xn) + a There are some values of a for which a positive starting value for x results in this formula converging to an integer. For example, if a = 2, you would observe…

## Sum of Powers

Find a combination of three different positive integers x, y, and z such that: x3 + y3 = z4 Hint: there’s a better way than brute force / trial & error.