MyntBit
Start free

Mental math · Speed Engine

Mental math practice for trading interviews

MyntBit's Speed Engine is free mental-math speed training built for quant and trading interviews. It's for candidates facing the timed arithmetic screens that gate trader roles: Optiver's 80-in-8 test, Jane Street's mental math rounds, and the numerical screens reported at SIG, IMC, and Akuna. Timed drills, firm-style scoring, and a leaderboard to benchmark your pace.

Start free drillExplore the quant trader track

Free · 60-second rounds · Practice & competitive modes · Leaderboard ranked

The screens

How firm math tests work

Most trading firms screen mental math before anything else. Formats change year to year, but the reported shapes fall into a few patterns — all of them timed, all of them punishing sloppy arithmetic.

Optiver · Reported format

Optiver 80 in 8

80 arithmetic questions in 8 minutes — about 6 seconds each. Scoring is widely reported as +1 for a correct answer and -1 for a wrong one, so blind guessing costs points. The screen rewards a steady pace with very few errors.

Optiver prep

Jane Street · Interview rounds

Jane Street mental math

Less a standalone speed test, more mental math woven into live probability and market-making rounds. You compute expected values, odds, and quick estimates out loud while explaining your reasoning to an interviewer.

Jane Street prep

SIG · IMC · Akuna

Numerical screens

Timed online numerical and arithmetic screens early in the trader pipeline. Reported formats vary by firm, office, and year — sequences, mental arithmetic, and estimation under a strict clock are the common threads.

SIG prep

Community standard

Zetamac-style sprints

Many firm screens resemble a Zetamac sprint: two-operand arithmetic, type the answer, next question, repeat until the clock runs out. If you can hold a fast Zetamac pace calmly, the format of most screens will feel familiar.

Try a sprint

Honest comparison

Zetamac vs MyntBit Speed Engine

Zetamac is the arithmetic game trading candidates have drilled for years, and it's genuinely good at what it does. Speed Engine is the trading-focused alternative. They solve different parts of the same problem.

The community default

Zetamac

Free, unlimited arithmetic sprints — two-operand addition, subtraction, multiplication, and division against a clock, with customizable number ranges. No account, no frills. It's the default warm-up for Optiver-style screens for a reason.

  • Unlimited free sprints, no signup
  • Customizable number ranges and duration
  • Pure arithmetic — no scoring penalties or rankings

The trading-focused alternative

MyntBit Speed Engine

Free 60-second drills built around how firms actually score: a sudden-death competitive mode, a forgiving practice mode, and a difficulty curve tuned for trading screens. Your runs feed a leaderboard, streaks, and per-session stats.

  • Firm-style scoring with practice and sudden-death modes
  • Leaderboards, streaks, and progress tracking
  • Sits inside a full quant prep platform

Our honest recommendation: use both. Drill Zetamac for raw arithmetic volume, then use Speed Engine to add scoring pressure, track your pace over time, and benchmark against other candidates.

After the speed test

Mental math is round one

Passing the arithmetic screen gets you into the rounds that actually decide offers: probability, brainteasers, and market making. MyntBit covers the whole pipeline.

Speed

All training games

Speed Engine plus the rest of MyntBit's timed games for calculation speed and market intuition.

Browse games

Depth

Question bank

1000+ quant interview questions — probability, brainteasers, and market making — tagged by the firms that ask them.

Open training

Structure

Quant trader track

A full prep sequence for trader roles: mental math first, then probability, options, and market-making games.

View the track

Frequently asked

Mental math for trading, answered

What mental math do trading firms test?
Mostly rapid arithmetic: addition, subtraction, multiplication, and division with integers, decimals, and fractions, plus percentages and quick expected-value estimates. Firms test speed and accuracy under time pressure rather than advanced math — probability questions and market games usually come in later rounds.
How fast do I need to be for the Optiver 80 in 8?
The reported format is 80 arithmetic questions in 8 minutes — an average of 6 seconds per question. Scoring is widely reported as +1 for a correct answer and -1 for a wrong one, so guessing is penalized. Candidates commonly cite pass marks in the 60s out of 80, which means you need both pace and a very low error rate.
Is Zetamac enough to prepare for trader interviews?
Zetamac builds the raw arithmetic speed you need, and many successful candidates drill it daily. It does not simulate the rest of the screen, though: penalty scoring, mixed question styles, or the probability and market questions that follow. A common approach is Zetamac for arithmetic volume plus a trading-focused tool like MyntBit's Speed Engine for firm-style pressure, then dedicated probability practice.
How long does it take to get good at mental math?
Most people see measurable speed gains within 2-4 weeks of daily 10-15 minute practice, and reach interview-ready pace in roughly 1-3 months depending on their starting point. Consistency matters more than session length — short daily drills beat occasional long ones, because speed comes from pattern recognition built through repetition.
What score is good on a mental math test?
It depends on the test. On the Optiver 80 in 8, commonly cited pass marks fall in the 60s out of 80 under +1/-1 scoring. On Zetamac's default settings, candidates targeting trading roles often aim for 50 or higher. On MyntBit's Speed Engine, 80+ calculations per minute with high accuracy is expert level. Treat all of these as guides — firms adjust cutoffs by role, office, and year.
Is MyntBit's Speed Engine free?
Yes. Speed Engine is free to play. Practice mode gives you 5 lives and a +5 second bonus per correct answer so you can build speed without pressure. Competitive mode is sudden death — one life, no time bonus — and ranks you on the public leaderboard.
Start free drill