Quant interview problems
Explore quantitative interview problems by topic, difficulty, and company. Practice probability, mathematics, and finance.
- 100 Light bulbs
- 100 Switches
- 1000 Stones
- 2 Eggs
- 2D Grid Game
- All Girls World?
- Ant Journey
- Antipodal Points with Equal Temperature
- Bid-Ask Spread as a Percentage of Mid
- Burning Cords
- Buy and Sell Stock: Optimal Time Complexity
- Cheating Husbands
- Correlation Under Linear Transformations
- Dark Room Deck
- Devil's Penny
- Door to Offer
- Duck & Fox
- Father of lies
- Filet Mignon
- Find the Variance
- First to 50
- Fox, Chicken, and Grain River Crossing
- Grid Fill
- Half Time
- Heaviest Coin
- Hilbert's Hotel: One New Guest
- Invisible Dice
- Knight and Knave
- Measuring 45 Minutes with Burning Ropes
- Measuring 9 Minutes with Hourglasses
- Monty Hall Problem
- Most Profitable Strategy
- Pair of Socks
- Pirate Gold Division
- Poisonous wine
- Pricing a Simple Coupon Bond
- Prisoner's Hat (Binary)
- Probability for Standard Normal Variables
- Rainbow Trains
- Rolling the bullet
- Sample Duplication
- Shooting in Circle
- Ten Topping Sundae
- The Clumsy Chemist
- The Plane in the Wind
- The Returning Explorer
- Time Value of Money: Monthly Compounding
- Unbiased Coin
- Water & Wine
- Which Switch?
- Witches at the coffee shop
- You have a train to catch!
- 2 Equations & 3 Unknowns
- Amazon Packages Delivered in the US Daily
- Americans in Movie Theaters on Friday Night
- Annual Calorie Consumption for an American
- Annual Milk Consumption in California
- Annual Revenue of a NYC Hot Dog Cart
- Annual Shipping Containers at Long Beach
- Annual Shoe Sales in the US
- Annual Tourists Visiting Paris
- Ants in a Typical Backyard
- Benches in Central Park
- Bicycles in Amsterdam
- Birds in New York City
- Blades of Grass on a Football Field
- Breaking Stick
- Breaths in a Human Lifetime
- Brownian Motion: Compute E[W_s W_t]
- Candy Game Convergence
- Catching Ants
- Cell Towers in the United States
- Chess Tournament
- Chi-Square Test for Independence: Compute the Statistic
- Chocolate Bar
- Chuck a Luck
- Coffee Served at a Busy Starbucks Daily
- College Students Currently Enrolled in NYC
- Color Complex
- Commercial Flights Worldwide Daily
- Confidence Interval Width Scaling with Sample Size
- Cost to Fill All US Gas Tanks
- Crazy Clock
- Crazy Postman
- Daily Credit Card Transactions in the US
- Daily Flights from JFK Airport
- Daily Gasoline Usage in Los Angeles
- Daily Google Searches Worldwide
- Daily Miles Traveled by NYC Subway Trains
- Daily Passengers on London Underground
- Daily Revenue of a McDonald's Restaurant
- Daily Transactions at a Bank Branch
- Daily Uber Rides in Manhattan
- Daily Vehicles Crossing the George Washington Bridge
- Daily Visitors to Central Park
- Dead Men Walking
- Delta of a European Call in Black–Scholes
- Diapers Used Before Potty Training
- Drunk Passenger
- Electrical Wire in a House
- Electricity Used by US TVs at Peak Time
- Elevators in Manhattan
- Elevators in New York City
- Emails Sent Worldwide Daily
- Equal Friend Counts at a Party
- Excel Spreadsheets Created Worldwide Daily
- Eye Blinks Per Year
- Fire Hydrants in San Francisco
- Forwards and Futures
- Fruit Magic
- Gamma of a European Call in Black–Scholes
- Gas Stations in the United States
- Global Daily Smartphone Sales
- Golf Balls in a School Bus
- Grains of Sand on a Beach
- Grocery Stores in Texas
- Haircuts Given in Manhattan Daily
- Hairs on a Human Head
- Minimum-Variance Futures Hedge
- Height of $1 Million in $100 Bills
- High School Teachers in the United States
- Hours Spent Sleeping in a Lifetime
- Human Heartbeats Per Day
- Illegible Dice
- Implied Volatility from an ATM Call Price
- Infinity & Beyond
- Innocent Monkey
- Ito Isometry: Var(∫ W_t dW_t)
- Jelly Beans in a Gallon Jar
- Job Interviews Conducted in the US Daily
- Joint Model Evaluation
- Leaves on a Mature Oak Tree
- Length of NYC Water Mains
- Light Bulbs in Circle
- Lucky Bubble
- Macaulay Duration of a 2-Year Coupon Bond
- Manhole Covers in NYC
- Martingale Property: E[W_t | F_s]
- Mental Math: 39 x 41
- Miles of Pipe in NYC Water System
- Miles of Wire in a Skyscraper
- Min & Max
- Mosquitoes Born Daily in Florida (Summer)
- Most Traded Stocks Data Structure
- MULTILINGUAL
- Multiple Regression: Interpreting a Partial Effect
- No-Arbitrage Forward Price
- Number of Double Heads
- Option Arbitrage
- Overlapping Coins
- Parametric 95% One-Day VaR (Normal Returns)
- Parking Spaces in a Major US City
- People Flying Over the US Right Now
- People in Times Square on New Year's Eve
- People on NYC Subway Right Now
- Piano Tuners in Chicago
- Pigeons in Manhattan
- Pizzas Consumed in NYC Daily
- Pizzas Ordered on Super Bowl Sunday
- Prisoner's Hat (multicolor)
- Quadratic Variation of Brownian Motion
- Rabbit on the Staircase
- Rainbow Hats
- Red Blood Cells in Human Body
- Regression Slope When Swapping X and Y
- Restaurants in the United States
- Risk-Neutral Drift for a Non-Dividend Stock
- Sample Size for a Desired Margin of Error (Proportion)
- Scaling a Square
- Second Chance
- Secure Document Delivery Protocol
- Sharing Wood
- Single Bid
- Smartphones Currently in Use in NYC
- Soccer Accuracy Paradox
- Square Infection Minimum
- Stars Visible on a Clear Night
- Steps Taken Per Year by Average Person
- Stick to Triangle
- Streetlights in Los Angeles
- Sum of Numbers from 1 to 100
- Taxi Cabs in New York City
- Taxis Operating in NYC Right Now
- The Blind Archer
- Theta via a One-Day Finite Difference
- Tiger and Sheep
- To Begin or Not to begin?
- Toilet Paper Sheets Used in the US Annually
- Toothbrushes Sold in the US Annually
- Total Handshakes Among Ten People
- Total Length of US Roads
- Traffic Lights in Manhattan
- Traffic Lights in NYC
- Trees in Central Park
- Type I/II Errors: Compute Test Power
- Uber Drivers Active in Manhattan
- UPS Delivery Trucks Nationwide
- US Vending Machine Industry Revenue
- USPS Mailboxes in Boston
- Vega: Price Change from an Implied Volatility Move
- Water Bottles Sold at a Stadium Per Game
- Water Bottles Sold at JFK Airport Daily
- Water in an Olympic Swimming Pool
- Water Used by NYC Daily
- Weight of Air in a House
- Weight of Cars in a Stadium Parking Lot
- Windows in the Empire State Building
- Angle Between Clock Hands at 12:15
- Arabian Sultan
- At Least 4 Heads in 7 Coin Flips
- AR(1) Autocorrelation at Lag 3
- Barrier Option Identity: Up-and-Out vs Vanilla
- Bayesian Coin Updating
- Birthday Day-of-Week Coincidence for Three People
- Black–Scholes Gamma Formula
- Black–Scholes PDE Form
- Bond Price Sensitivity Using Duration and Convexity
- Bowling Ball Weight Scaling by Diameter
- Bricking Box
- Bullets of Fate
- Call Option Payoff at Expiration
- Call Option vs Stock: Key Advantage
- Cards Reordering
- Catching the Spy
- Catching the Submarine
- Chicken Egg Production Rate
- Clan Size
- Clock Angle at 10:45
- Clock Hand Angle at 3:15
- Clock Hand Angle at 9:45
- CLT Bounds: Berry–Esseen Sample Size
- Collecting Lucky Coupons
- Color Switches
- Combined Work Rate Problem
- Combined Work Rate: Two Painters
- Compound Interest Calculation
- Computing the Nth Fibonacci Number Efficiently
- Diverging Roads: Truth-Teller and Liar Puzzle
- Drawing Two Cards of the Same Color
- e^Pi or Pi^e
- Effect of Volatility on Option Moneyness Probability
- Eight-Letter Word with Letter Values Summing Below 50
- Expected Breakup Length
- Expected Flips to Get Two Heads
- Expected Flips Until First Heads on Fair Coin
- Expected Heads in 100 Coin Flips
- Expected Value of Dice Rolls
- Finding an Anti-Terrorist Agent
- Free Sundae
- Game of Divisors
- Gas Stations on Circular Trek
- Greed for an ACE
- Growing Fund: SQL Approach
- Half Heads
- Ito’s Lemma: Drift of log(S_t) under GBM
- Last Digit of 2^230
- Left Some Candies
- Linear Regression MLE Closed-Form Solution
- LLN Rate: Chebyshev Sample Size Requirement
- Lucky Candy
- Messing with Envelops
- MLE for a Poisson Rate Parameter
- Multicollinearity Effects in Regression
- Next Clock Hand Overlap After Noon
- Next Term in Fibonacci Reciprocal Sequence
- Order Statistics: Probability the Maximum is Below a Threshold
- Prisoner's Hat (Infinity)
- Probability All Three Coin Flips Match
- Probability of Even Heads in N Coin Flips
- Probability of Odd Number of Heads in Fair Coin Tosses
- Probability of Sum 10 with Three Dice
- Probability Two Dice Sum to Seven
- Pure Gold
- Put-Call Parity: Solve for the Put Price
- Regression Diagnostics: Test for Heteroskedasticity
- Risk-Neutral Drift with Continuous Dividend Yield
- Scaling Bowling Ball Weight by Diameter
- Sharing a Secret (Keys)
- Sharing a Secret (Locks)
- Sufficient Statistic for Exponential Rate
- Sum of Odd Numbers from 1 to 50
- The Lucky Door - Monty Hall Variant
- Time Series Stationarity: AR(1) Condition
- Top Buyer and Seller: SQL Approach
- Two Children: Younger is a Girl
- Two-Asset Portfolio VaR with Correlation
- Volatility and Call Option Prices
- Card Deck Comparison: Probability of Two Red Cards
- Primality of 1027
- 12-Ball Weighing Problem
- 3Sum Closest
- Annual Bitcoin Mining Energy Consumption
- Bayesian Analysis of Negative Cancer Test
- Bayesian Inference with Unreliable Witnesses
- Bayesian Urn Selection After Drawing $10 Chip
- Best-of-Three Tennis Match: Two Sets vs Three Sets
- Boy or Girl Paradox: Two Children Probability
- Bus Passengers with Fractional Exits
- Calculate Group Average Salary While Keeping Individual Salaries Private
- Calculate Test Score with Penalty for Wrong Answers
- Cards Needed for 100-Level Card Tower
- Circular Seating in Birthday Order
- Closest Median Profit: SQL Approach
- Coffee Consumption on NYSE Floor
- Coin Flip Competition: 17 vs 16 Coins
- Coin Guessing Game: Probability of Winning
- Conditional Card Drawing: Heart Probability
- Conditional Expectation of Gaussian Given Sum Constraint
- Coupon Collector Problem: Expected Die Rolls to See All Faces
- Creating Fair Coin from Biased Coin
- Daily Bloomberg Terminal Keystrokes
- Daily Canceled HFT Orders
- Daily Excel Files in Finance
- Die Roll with Optional Reroll
- Die Rolling Game: Maximize Sum Without Busting
- Distribution of Sum of Two Uniform Random Variables
- Drawing Balls Until One Color Exhausted
- Effect of Duplicating Data in Linear Regression
- Evaluate Betting Strategy for HHH with Given Odds
- Even Sum from Three Random Primes
- Exact Probability of 50 Heads in 100 Fair Coin Flips
- Expected Card Value in Standard Deck
- Expected Flips for Three Consecutive Heads
- Expected Maximum of Two Dice
- Expected Samples Until Sum Exceeds One
- Expected Sum Given At Least One Six
- Expected Tosses for N Consecutive Heads
- Expected Value vs Risk: Coin Flip Betting Games
- Expected Waiting Time in Poisson Process
- Expected Winnings in Dice Comparison Game
- Fermi Estimation: Stars vs Sand Grains
- Find the Heavier Ball in 12 with Minimum Weighings
- Geometric Series and Quick Probability Calculations
- Global Daily Text Messages
- Global Derivatives Notional Value
- Grand Slam Tournament
- Group Duplicate Numbers by First Occurrence Order
- HHT vs HTT Pattern Race
- Hours of Video Uploaded to YouTube Daily
- Identify Copper Coins Box with Single Weighing
- Kelly Fraction for an Even-Money Bet
- Key Difference Between Option and Futures Pricing Inputs
- King's Salary
- Largest Amount Unattainable with 5¢ and 11¢ Stamps
- Largest Number with Digit Product 120
- Linear Interpolation on 2D Points
- Look-and-Say Sequence
- Manhattan Uber Rides During Market Hours
- Maximum Product of Three Numbers
- Mental Long Division: 2 Divided by 17 to Four Decimals
- Minimum Races for Top 3 of 20 Horses
- Monte Carlo Estimation of Pi
- Mutilated Chessboard and Domino Tiling
- Mutilated Chessboard Domino Covering (Why Impossible)
- Nim-like Game to 15 with Picks of 1 or 2
- Nomadic Manager: SQL Approach
- Normal Approximation for Binomial: At Least 50 of 400 Pass
- NYSE Orders Per Second at Peak
- Odd Heads with Mixed Fair and Biased Coins
- Optimal Point Minimizing Sum of Absolute Distances
- Optimal Question for Guessing Coin Sequence
- Pattern on Snowflakes
- Pattern Recognition: Find Next Term
- Phone Number Coincidence: Chance or Significant?
- Physical Gold in ETF Vaults
- Pigeonhole: Five People Sharing Birth Month
- Probability Black Balls Are Not Adjacent
- Probability of Even Heads with N Fair Coins
- Probability of Game 7 in Best-of-Seven Series
- Probability of Meeting at Train Station
- Probability of More Than 550 Heads in 1000 Coin Flips
- Probability of Strictly Increasing Die Sequence
- Probability Product of Two Dice is a Perfect Square
- Quick Mental Math: 0.01-Wide Interval for 3/12
- R-Squared Symmetry: Regressing Y on X vs X on Y
- Random Ratio
- Reconstruct Five Numbers from Their Ten Pairwise Sums
- Red-Black Card Game with Optional Stopping
- Rolling Mean and Variance in O(1) Time
- Secure Average Salary Computation
- Simpson's Paradox: Identifying the Scenario
- Smallest Integer with Digit Product 10,000
- Smallest Multiple of 15 Using Only 0s and 1s
- Smallest Multiple of 77 Exceeding 70,000
- Smallest Number with Digit Product 10,000
- Smallest Number with Digit Product 216
- Strategic Dice Betting with Information Asymmetry
- Sum of Consecutive Integers
- Tennis Game Win Probability from 30-30 with 70% Point Advantage
- Tennis Win Probability from Deuce with 60% Point Win Rate
- Texas Crypto Mining Electricity
- Three Light Switches and Three Bulbs
- Three Random Dots on Square Edges
- Two Burning Strings: Measuring 45 Minutes
- Two Children Problem with Named Child (Tom)
- US Strategic Petroleum Reserve Capacity
- Valid Range of Common Correlation for Three Random Variables
- Water Jug Puzzle: Measuring 4 Gallons
- Weekend Pizza Probability
- Weekend Rain Probability (Independent Events)
- World Series: Probability of Going to 7 Games
- 2D Grid Game II
- Ball Color Guessing Game: Expected Winnings
- Colored Runs of Cards
- Consecutive Sums
- Dice Ratio Game: Choose Best Payout
- Distance from North Pole
- Expected Count of Uniform Variables Until Sum Exceeds One
- Expected Distinct Values in Sampling with Replacement
- Expected Rolls for Two Consecutive Sixes
- Expected Uniform Samples Until Sum Exceeds One
- Explicit Solution to GBM
- Feynman–Kac: PDE to Expectation
- Frog Cover Time on 4 Circular Lily Pads
- Girsanov: Brownian Motion under Measure Change
- Guaranteed Outcome Betting on Seven-Game Series
- Intersecting Cylinders (Steinmetz Solid)
- Maximum R² from Combined Predictors
- MGF of an Exponential Random Variable
- Minimum Races to Find Top 3 of 25 Horses
- Number of Digits in 99^99
- Optimal Door Selection: Three Coin Tosses
- Ornstein–Uhlenbeck Process: Mean Function
- Padel Game Win Probability at 9-9 Against Stronger Opponent
- Place or Take
- Poisoned Cake Identification
- Private Average Salary Calculation
- Random Point on Disk
- Random Walk on Cube: Expected Steps to Opposite Corner
- Random Walk: Reaching Target Before Barrier
- Sports Betting Arbitrage with Plus Odds
- Sum of Uniforms Exceeding One: Expected Count
- Taxman Game: Maximize Your Score (N=6)
- Ten Prisoners Hat Puzzle - Parity Strategy
- The Noodles: Expected Loops
- Three Fishermen Dividing Fish
- Two Egg Problem: Minimum Worst-Case Drops
- Unique Pairwise Digit Sums: Why 7 Digits Fails
- Upper Bound on Third Correlation Given Two Others
- Valid Range of Equal Pairwise Correlations for N Variables
- Variance of X-Coordinate for Uniform Points on Unit Circle
- Weekend Rain Probability Bounds (No Independence Assumption)
- Weights Reckoning
- Winner's Curse Bidding Problem
- Airplane Boarding: Last Passenger's Seat
- FX Volume Around Economic Releases
- Global Interest Rate Swap Notional
- Quant Fund GPU Backtesting Hours
- Enclosing The Center
- Moser's Circle Problem: Regions from N Points
- How Many Times Has "Priced In" Been Said Since 2008?