Quant interviews are timed.
Practice that way.
Probability, expected value and mental arithmetic under a clock — the reasoning that online assessments lean on hardest.
Free, 23 games. Mental Math high score 26, held by hedgehog-goshawk-2452.
Today's Challenge
6 questions · the same for everyone · new at midnight UTC
The games
All 23, free, unlimited. Probability first — it's what timed assessments lean on hardest.
Probability & Expected Value
The core of most quant and trading online assessments. Conditional probability, expected value, and bet sizing under a clock.
Probability Blitz
Rapid-fire probability questions: coin flip combinations, dice sums, card draws. Answer within tolerance before time runs out.
Leaderboard →Expected Value Challenge
You're offered a bet with a win amount, a loss amount, and a probability. Decide fast whether the expected value says take it.
Leaderboard →Bayesian Updating
Start at a 50/50 prior, observe a sequence of flips, and update to the correct posterior probability.
Leaderboard →Conditional Probability
The probability questions people actually get wrong: conditional probability, Bayes, cards without replacement, Monty Hall.
Leaderboard →Kelly Criterion
Given an edge and the payout odds, compute the Kelly-optimal fraction of your bankroll to bet.
Leaderboard →
Mental Math & Recall
Raw arithmetic speed and working memory — the baseline every timed test assumes.
Mental Math Sprint
Add, subtract, multiply, and divide against the clock. Every problem sits at the same intermediate difficulty, so your score reflects speed, not luck of the draw.
Leaderboard →Number Memory
A digit string flashes on screen, then disappears. Type it back. Each round adds a digit — one mistake ends the run.
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Trading & Markets
Reading a book, quoting a market, and tracking a position's P&L.
Market Making
Post a bid/ask spread against a hidden fair value. Counterparties trade against you — a tight, well-centered quote wins; a wide or mispriced one loses.
Leaderboard →Mental Order Book
A live bid/ask book flashes on screen. Spread, mid price, walk-the-book fill price — answer before time runs out.
Leaderboard →Trading P&L Sprint
Track a rapid sequence of buys and sells at an average cost basis, then compute realized, unrealized, or total P&L before time runs out.
Leaderboard →Rapid Graph Interpretation
A bar chart flashes on screen, then disappears. Recall the max, the min, or a specific value from memory.
Leaderboard →Data Intuition
Short scenarios testing statistical intuition: confounders, sample size, R², and the causation trap.
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Reasoning & Logic
Deduction, estimation, sequences, and game theory.
Sequence Recognition
Arithmetic, geometric, square, and Fibonacci-style sequences. Spot the rule and enter the next number before the streak breaks.
Leaderboard →Fermi Estimation
Order-of-magnitude estimation questions. You don't need to be exact — you need to be in the right ballpark, fast.
Leaderboard →Logic Deduction
Short constraint puzzles — three or four clues, one valid conclusion. Interview-style logic, not LSAT-length.
Leaderboard →Optimization Challenge
Two bets, one choice. Compute the expected value of each and pick the one that actually maximizes it.
Leaderboard →Game Theory
A simple payoff matrix and an opponent's move. Find the row that maximizes your payoff against it.
Leaderboard →Information Value
A bet, and a price to learn the outcome in advance. Decide whether the information is worth more than it costs.
Leaderboard →Quant Guessing Game
A hidden number 1-100. Each guess tells you higher or lower — find it in as few guesses as possible.
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Combined Challenges
Several games back to back, scored as one run.
QAM Assessment
The full test: mental math, probability, sequences, order books, trading P&L, and Bayesian reasoning rotate in one timed run. Ends with a percentile profile across every category and your best-fit interview tracks.
Leaderboard →Combo-5
Play all 5 Core games once each in a row. Your combined score ranks you on the Combo-5 leaderboard.
Leaderboard →Combo-10
The 5 Core games plus Market Making, Mental Order Book, Trading P&L Sprint, Conditional Probability, and Kelly Criterion — one round each.
Leaderboard →Combo-15
Combo-10 plus Fermi Estimation, Bayesian Updating, Logic Deduction, Optimization Challenge, and Game Theory — the full 15-game run.
Leaderboard →