The Radix Trading Probability & Numerical interview is stage 3 of 5 in the Radix Trading interview process, after the C++ & Algorithms (online assessment). Format: 45-60 min - video. Probability, combinatorics, and statistics with a numerical bent (variance computation, sampling).
Preparing for this round? Practice the 15 questions mapped to the Radix Trading Probability & Numerical, with worked solutions. A free account saves your progress.
What the Probability & Numerical tests
QuantVault maps 15 practice problems to this round. By topic, the biggest groups are probability (8), combinatorics (5), statistics (2); by difficulty, 4 easy, 11 medium and 0 hard. 6 of them were reported by candidates who interviewed at Radix Trading, most recently in Jun 2026.
How to prepare for the Probability & Numerical
- Sampling -- uniform paths, returning walks.
- Clean combinatorial counting.
Further reading: How quant superdays work · Behavioral questions at trading firms · Market-making game interview guide.
Question types in this round
The 3 largest question types in the Radix Trading Probability & Numerical practice set; across them the most common sub-topics are numerical methods, symmetry, uniform distribution, binomial distribution, conditional probability, discrete probability. The questions themselves, with worked solutions, are in the round practice.
Probability8 in this round
Combinatorics5 in this round
Statistics2 in this round
Common mistakes
- Variance computation -- avoid catastrophic cancellation.
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Frequently asked questions
What is the Radix Trading Probability & Numerical interview?
It is stage 3 of 5 in the Radix Trading interview process, after the C++ & Algorithms (online assessment). Format: 45-60 min - video. Probability, combinatorics, and statistics with a numerical bent (variance computation, sampling).
How long is the Radix Trading Probability & Numerical interview?
Candidates report: 45-60 min - video.
What questions come up in the Radix Trading Probability & Numerical interview?
The practice set QuantVault maps to this round centers on probability, combinatorics, statistics.
How should I prepare for the Radix Trading Probability & Numerical interview?
Sampling -- uniform paths, returning walks. Clean combinatorial counting.
What comes after the Probability & Numerical?
The Linear Algebra & Optimization (stage 4 of 5). Format: 45-60 min - research.
Practice the Radix Trading Probability & Numerical round
Work the 15 mapped practice problems with progress tracking, then move to the next stage of the Radix Trading funnel.