The arithmetic screen is the first thing almost every trading firm puts in front of a candidate, and it eliminates more people than any interview. This drill runs the two formats that matter.
Start the Mental Math Trainer drillFree, runs in your browser, nothing to installThe mental-math screen does not test mathematical ability. It tests whether arithmetic has become automatic. A trader pricing a market cannot spend four seconds on 7 × 84 — the market has moved. Firms therefore filter on raw calculation speed before anyone spends interview time on you.
That is good news: unlike probability puzzles, this is a skill that improves reliably with a few minutes of daily practice. Most candidates who fail here simply never drilled it.
The classic timed drill. Questions come one after another for a fixed period, usually two minutes. Wrong answers cost nothing — the question simply does not advance. Your score is how many you clear. This is the format the widely-used free tool Zetamac made standard, and it is the right way to build raw speed.
The 80-in-8 exam. Eighty questions, eight minutes, scored +1 for correct, −1 for wrong, and −1 for skipped. That scoring changes the strategy completely: because skipping costs exactly as much as answering wrongly, you should always guess rather than leave a question blank. A wrong guess and a skip cost the same, but the guess can be right.
On an 80-in-8 style assessment, roughly 55 is a commonly cited pass mark and 70+ is competitive. On a two-minute classic drill, 20 is a starting point, 40 is solid, and 60+ is trading-desk strong.
These are rules of thumb from candidate reports, not official figures — firms do not publish thresholds, and they vary by role and year.
Short and daily beats long and occasional. Ten focused minutes a day for two weeks will move your score more than a three-hour session on the weekend.
Drill your weakest operation on its own. Most people are far slower at division than addition, and the mixed drill lets you hide from it. Use the operation toggles to isolate the one costing you time, then return to the mixed format.
Learn the shortcuts that actually come up: multiplying by 5 is halving then ×10; ×9 is ×10 minus the number; two-digit squares near 50 have a quick form. Speed comes from recognising patterns, not from thinking faster.