What a Coincidence! How surprised should we be to find a common birthday in a random group of people?

Apples & Oranges In front of you are three boxes. One contains only apples, one contains only oranges and one contains a mix of apples and oranges.

Ones and Zeros What is the smallest number evenly divisible by 225 that contains only the digits 1 and 0?

This Puzzle has its Ups and Downs Let’s imagine that at noon one day you set out from the base of Mt. Rainier and you reach the summit exactly 24 hours later...

Palindromically Speaking Palindromes are normally words, but we're going to try to find calendrical palendromes

Weighing Your Options Imagine you have nine uniformly sized white balls, eight of which weigh precisely the same amount, and one is decidedly heavier or lighter than the rest...

Putting Your Cards on the Table In front of you are four cards on a table. Each card has a letter on one side and a number on the other side.

An Open and Shut Case Imagine you’re standing at one end of a corridor, with exactly 100 lockers all in a row, numbered 1 to 100...

How Much Does a Brick Weigh? From the fertile mind of the late, legendary puzzle master Martin Gardner