Brain teasers, puzzles, riddles, and other challenges
The middle four letters of these 8-letter words are shown. Can you figure out the full 8-letter words? There may be multiple suitable answers for some of the words.
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 been inscribed such that one side lines up with the hypotenuse of the right triangle.
Is the inscribed square on the left larger or the one on the right?
Continue reading “Inscribed Squares”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?
What is the smallest number you can make by moving exactly 2 matches above?
Continue reading “Matchstick Minimization 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?
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 of?
Continue reading “Reverse the Digits and Add”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 card is face-up, otherwise all pairs are equally likely to be selected). Both cards are then flipped over (face-down to face-up or face-up to face-down).
Prove that after enough turns, it will eventually be impossible to select a pair of cards with the left card face-down.
When you reach this card flipping endgame, will the rightmost card be face-up or face-down?
Continue reading “Card Flipping Endgame”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 in the milk glass into the chocolate milk glass.
When they’re done, is there more chocolate milk in the milk glass or more milk in the chocolate milk glass?
Continue reading “Drink Mix Riddle”
