Quant Ladder

An 8-Week Quant Interview Preparation Plan That Actually Fits Around a Degree

3 min read

Most quant-prep advice fails on contact with a real schedule. It assumes unlimited time, front-loads theory, and leaves the two most heavily-weighted skills — timed arithmetic and live market games — for "later," which means never. This plan is built the other way around: 45–60 minutes a day, skills ordered by how long they take to build, everything timed from day one.

The ordering principle

Different interview skills respond to training at very different speeds:

  • Mental math improves for weeks and decays fast → start immediately, never stop.
  • Probability fluency builds steadily with spaced practice → the core of the middle weeks.
  • Market-game instincts transfer quickly once fundamentals exist → concentrated late.
  • Behavioral/"why trading" needs hours, not weeks → the final week.

Daily structure throughout: 10 minutes mental math + 35–50 minutes of the week's focus. The mental-math block is non-negotiable; it's the compounding asset.

Weeks 1–2: Foundations under a clock

  • Daily timed mental-math session. Week 1 is diagnostic — find your weak operations. Week 2, drill them specifically.
  • Probability: one focused set per day at moderate difficulty — conditional probability, expectation, linearity. Write out your reasoning even when the answer is obvious; the interviews are oral.
  • End of week 2 checkpoint: you should be attempting 45+ arithmetic questions at 90%+ accuracy, and setting up P(A|B) problems without hesitation.

Weeks 3–4: Expected value and the classics

  • Work through the canonical families, one per session: optimal stopping (die re-rolls), first-passage (flips until HH), coupon collector, gambler's ruin, symmetry arguments (first ace, points on a circle).
  • For every problem, do the three-question extension: Which way does the answer move if a parameter changes? What does the distribution look like, not just the mean? Would I bet on this at 2:1?
  • Don't grind volume. Twenty problems understood to follow-up depth beat a hundred recognized.

Weeks 5–6: Market games and combinatorics

  • Add two or three market-making game rounds per week. Learn the quoting loop: fair value out loud → spread from uncertainty → update on every fill → respect inventory limits. The first few rounds will go badly; that's the point of doing them now and not in the interview.
  • Keep one probability set per day, now at higher difficulty and mixed categories, so retrieval stays warm.
  • Combinatorics gets its own two sessions per week — counting arguments (lockers, tournament brackets, horse races) reward pattern exposure more than theory.

Week 7: Full-pressure integration

  • Simulate real conditions: one full-length mental-math test and one long mixed problem session daily, at the time of day your interviews will be.
  • Practice speaking solutions — to a friend, a rubber duck, or a wall. The single most common failure at onsites is silent computation. Ninety seconds of confident, structured narration with a small arithmetic slip beats a silent perfect answer.
  • Play market games with someone adversarial if you can. You need the experience of being picked off by informed flow at least a dozen times before it stops stinging and starts informing.

Week 8: Taper and specifics

  • Halve the volume. Like any performance event, you want to arrive sharp, not exhausted.
  • Research your specific firms: Optiver leads with arithmetic; Jane Street goes deep on probability conversation; SIG loves poker-flavored decision questions; research shops add statistics and a project conversation. Adjust the final week's emphasis accordingly.
  • Prepare your three stories: why trading, a decision you made under uncertainty, a time you were wrong and updated. Quants underprepare these because they're "soft" — then deliver them badly to interviewers who weight them heavily.

The meta-rule

Consistency beats intensity everywhere in this plan. Eight hours on Saturday is worth less than one hour daily — retrieval practice, spacing, and pressure-tolerance all come from frequency, not duration. Protect the daily streak ruthlessly; it is the entire mechanism.

Quant Ladder is built around exactly this loop — adaptive daily practice, a timed mental-math trainer, and a scored market-making simulator — with a streak to protect. The trainer is free; start today and the plan starts itself.