Quant probability and mental math practice
Five short problems in 30 minutes: expected value, combinatorics, conditional probability, estimation and market making. Reason out loud; once you answer, Vera asks you to check it or extends the problem once.
- 30 min
- Five short ones
- Up to two small nudges
- Quant developer (C++)
How the round runs
- 01
The problem
Vera asks one short problem. Restate it, ask about anything ambiguous, and start reasoning out loud.
- 02
Reasoning against the clock
Time pressure is part of the round. Set the problem up, say the key idea and work toward a number. If you go quiet for long, Vera prompts you.
- 03
Check or extend
Once you answer, Vera asks you to sanity-check it or changes the problem once, then moves to the next one.
What the report scores
Each skill gets a score from 1 to 5 against the bar for your level, with the quotes it is based on and the time you said them. The report ends with one thing to fix next.
- Correctness
- Structured reasoning
- Speed and estimation
- Communication
At lead level, also: Market intuition.
How the real round works
Probability and mental math rounds are a gate for trader roles and appear lightly in some quant developer loops: short problems on expected value, conditional probability and combinatorics, worked out loud against the clock, and in trader finals a market-making game. The guides we read agree that structure, sanity checks and calm under pushback count as much as the final number.
How quant probability interviews work: structure, signals and common mistakesRegular and lead level
- Regular
- Correct answers with structured reasoning, reached quickly, and a check on the result.
- Lead
- Also market intuition: connect the results to pricing, risk and the decision you would make.
Length: 30 minutes at either level.
See the feedback before you start
Full reports from the real report pipeline, for a fictional student and a scripted interview.
Questions
Do quant developer interviews really ask probability?
Some do, lightly. The guides we read say developer loops at trading firms are mostly C++ and systems, with probability as a short puzzle at some firms and a full round in trader and hybrid roles. Practise it if your target role leans that way.
Is there a market-making game?
Market-making questions are asked like the others, with a follow-up, for example how you set your bid and ask and what a trade tells you. Vera does not run a live trading game.
Can I use paper?
Yes. Work on paper if it helps, but say the steps out loud: the reasoning you speak is what the report scores.
What does the report score?
Correctness, structured reasoning, speed and estimation, and communication, plus market intuition at lead. Each score quotes what you said.