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 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?

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…

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…

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…

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…