Math Paradoxes

At a glance

Math Paradoxes is a no-sign-up browser site of 63 probability and logic puzzles, from Monty Hall and the birthday paradox to the German tank problem. Each puzzle page asks you to lock in a guess, then lets you play the game, run thousands of simulated trials and read several separate explanations. Worth a visit if a counterintuitive answer has ever left you unconvinced by the formula alone.

Good fit

Curious adults, students and teachers who want to see a probability result happen rather than memorise it, and interviewers who use logic puzzles. Pages are tagged For everyone, School maths or Advanced, and topic filters cover interview puzzles, conditional probability, statistics and biases, and games and strategy. Six themed courses aim at marketers, managers, product teams and job candidates, for example A/B testing in plain words.

Consider something else when

You want a structured maths curriculum with exercises and progress tracking, or topics outside probability, statistics, game theory and logic puzzles. Each page is built around one famous puzzle, so it suits short sessions of curiosity better than systematic study of a subject.

Start here

Open the Monty Hall problem from the All puzzles list. Read the five rules the host follows, then in Round 2, Pick a door, play 15 to 20 rounds and try both staying and switching. The Your session panel shows how often each strategy won. Then press Go on to see 10,000 simulated games, six explanations and the 20-door version.

Cost and requirements

Everything runs in a web browser with no sign-up, in English and Ukrainian. The site shows no price or paid tier for puzzles or courses. Two optional extras ask for more: commenting in each page's Discussion section requires a GitHub account, and the newsletter asks for an email address.

Limits to know

The catalogue covers probability, statistics, strategy and logic puzzles only. The author, Dmytro Kudrenko, says the site was built together with AI and that puzzles are still being added, so coverage grows over time. The game panels warn that a few rounds swing a lot, so your own session results can mislead until you run the larger simulation.

Still unclear

• Whether the interactive games and simulations work well on a phone screen.
• Whether the six courses are entirely free and complete, since no course page states its terms.