Top 30 Brainteaser and Mental Math Interview Questions
The most frequently asked questions on this topic across all roles and companies, ranked by real interview frequency. Updated daily.
Compute the probability that the sum of two fair dice is greater than 8 by counting favorable outcomes.
BloombergSSig
SmartestenergyCalculate the probability of observing at least two heads in three independent fair-coin tosses using the binomial distribution.
INGUse expected value and variance to price a 100-flip biased-coin game and determine the fair entry fee for a risk-neutral player.
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CitigroupAABN AMROCalculate the expected value of a die game and decide whether a risk-neutral player should accept it.
GICKKeyrock
Prudential Ins Co Of America InSign up to see every question
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Use conditional probability and independence to determine the chance of a second head after observing a first head.
The AmeripriseDDimensional Fund AdvisorsRRich RobustCompute the probability of HH from a biased coin using conditional probability.
CitadelUse independence and Bayesian updating to determine the next-flip probability after ten observed heads.
NatWestAAlphaGrep Securities
BarclaysDetermine how many consecutive heads are needed to reach 99% posterior confidence that a selected coin has two heads.
Trexquant Investment
Prosper MarketplaceGG-20 Group