Quant mental math tests are timed, no-calculator arithmetic screens that trading firms use to cut the applicant pool early. The benchmark example is Optiver's 80-in-8 — 80 multiple-choice questions in 8 minutes, about six seconds per question, with a −1 penalty for every wrong answer — and on Zetamac-style 120-second sprints, candidate-reported benchmarks put roughly 50 at a solid prep baseline and 70+ at competitive for top market makers. This page covers what each firm runs, the four skills being tested, and how to train them — starting with a ten-question drill you can take right now.
Try it: a 10-question speed drill
Zetamac-style rules: the answer submits itself the moment you type it correctly, so there is nothing to click and no penalty — your time is your score. Finishing at 6 seconds per question is 80-in-8 pace.
10 questions · addition, subtraction, multiplication, division · timer starts on click.
Why trading firms screen on arithmetic
No desk prices anything by hand — the software does that. Firms keep the arithmetic screen because it is cheap to run, nearly impossible to fake, and correlates with two things they care about: whether numbers feel like native language to you, and whether you stay composed when a clock is running and you have just made a mistake. It is also unapologetically a filter: a strong score gets you nothing except the next round, while a weak one ends the process on day one. That asymmetry should shape your prep — train to clear the bar with margin, then spend the rest of your time on the probability and expected-value questions and market games that actually decide offers.
The screens, firm by firm
| Firm / test | Format | What makes it distinctive |
|---|---|---|
| Optiver 80-in-8 | 80 questions, 8 minutes, four-option multiple choice | +1 / −1 scoring and no skipping — guessing is actively punished. Candidate reports put the pass line near 55 net. Part of the wider Optiver online assessment alongside Number Logic and the Zap-N cognitive games. |
| Flow Traders | Short timed arithmetic section | Heavy on fractions, decimals and percentage conversions rather than raw multiplication — the classic place candidates lose time is not knowing 1/12 ≈ 0.083 on sight. |
| Old Mission Capital | Math and probability speed multiple choice | Mixes plain arithmetic with quick probability and expected-value one-liners, so pure sprint training only covers half of it. |
| CTC (Chicago Trading Company) | Aptitude-style OA | Candidate-reported blend of numerical reasoning, sequences and probability rather than a bare arithmetic sprint. |
| Zetamac-style sprints | 120-second add/subtract/multiply/divide sprint | Not an official firm test, but the community benchmark that several firms' screens resemble — see our Zetamac score guide. Verbal mental math also shows up live at firms like SIG. |
The four skills actually being tested
- Raw four-operation speed. Two-digit addition and subtraction without visible effort, times tables comfortably past 12, and division reframed as multiplication. This is the layer Zetamac-style sprints train directly.
- Fraction ↔ decimal ↔ percentage fluency. Knowing 1/8 = 0.125, 3/8 = 0.375, 1/6 ≈ 0.167 and 1/16 = 0.0625 on sight, and swapping percentages (16% of 25 = 25% of 16 = 4). Flow-style tests live almost entirely here.
- Missing-operand equations. The 80-in-8's second question shape —
66 × ? = 138.6— is a division in disguise. Recognizing that instantly is a trained reflex, and it is the shape that most reliably trips first-time takers. - Sequences and patterns. Several OAs fold number sequences into the numerical section; the eight recurring pattern types cover nearly everything that appears.
Tests with negative marking add a fifth, sneakier skill: judgment under a penalty. With +1 / −1 scoring, an answer at below 50% confidence has negative expected value — knowing when not to answer is worth real points, and it is exactly the expected-value instinct trading firms want to see anyway.
Benchmarks: how fast is fast enough?
All public numbers are candidate-reported — firms do not publish cutoffs — but the folklore is consistent enough to plan around:
- 80-in-8: ~55 net is the commonly-reported pass line; ~70+ is competitive at the top desks. Finishing all 80 means ~6 seconds per question.
- Zetamac default settings: below 40 means you are not ready to apply; 45–55 is a workable baseline; 55–70 is competitive for most prop shops; 70+ means arithmetic will never be the reason you are cut. Full breakdown in the Zetamac practice guide.
- Pace, not volume, is the constraint. A clean 5–7 seconds per mixed-operation question, sustained for the full clock, clears essentially every arithmetic screen in the industry.
How to train
- Technique before timer. Learn the core toolkit — anchor-and-adjust (68 × 74 = 68 × 75 − 68 = 5032), difference of squares (62 × 58 = 3600 − 4), overshoot division — from the mental-math tricks playbook, and drill untimed until accuracy is above 95%.
- Daily timed sprints with an error log. Two or three short sessions a day beat weekend marathons; arithmetic speed is retrieval fluency and consolidates with spacing. Most people find 70% of their misses come from two operation types.
- Add the penalty. Once you are fast, practice under +1 / −1 scoring on the 80-in-8 simulator so skipping discipline is a habit, not a test-day improvisation.
- Finish with full-format simulations. Run the complete assessment for your target firm — the Optiver OA, Flow Traders OA, or the Zap-N games — at the time of day your real test is scheduled.
For a structured week-by-week version of this progression, see the mental math training plan.
Where to practice, free
Everything below runs in the browser with no signup: the Optiver 80-in-8 simulator in the exact format with scoring and advice, the Zap-N cognitive games, the speed-tricks playbook, and the market-making and trading games where the arithmetic finally gets used for something.
Frequently asked questions
What is a quant mental math test?
A timed, no-calculator arithmetic screen used by trading firms early in the hiring process. The best-known example is Optiver's 80-in-8 — 80 multiple-choice questions in 8 minutes with a −1 penalty for wrong answers — but Flow Traders, Old Mission, CTC, SIG and others run their own variants covering integers, decimals, fractions, percentages and sequences.
How fast do I need to be for trading firm mental math tests?
Finishing Optiver's 80-in-8 means averaging about six seconds per question. On Zetamac-style 120-second sprints, candidate-reported benchmarks put roughly 50 at a solid prep baseline and 70+ at competitive for top market makers. These are community numbers, not official cutoffs — firms do not publish thresholds.
What skills do quant mental math screens actually test?
Four things: fast four-operation arithmetic on integers, fluent fraction-decimal-percentage conversion, missing-operand equations (66 × ? = 138.6), and number-sequence pattern spotting. Negative marking on tests like the 80-in-8 also tests judgment — knowing when an answer is not worth the guess.
How should I train mental math for quant interviews?
Accuracy first, then speed: memorize squares to 25², the 1/6-through-1/16 decimal conversions, and the core multiplication tricks, then move to daily timed sprints with an error log, and finish with full-length simulations of the exact test format you will face — including negative marking if your target firm uses it.
Practice the real thing
The 80-in-8 simulator, Zap-N games, trading games, and ~400 problems with full solutions are free — no card, no signup.