My Quant Journey
Mental Math

Quant mental math practice, Optiver-style

Fast, accurate arithmetic under time pressure is the first filter at most trading firms. Train it with timed sprints, +1 for a hit and -2 for a miss, exactly the format Optiver made famous. Free, in your browser.

The classic Optiver test throws 80 questions at you in 8 minutes and rewards speed with accuracy: each correct answer is +1, each wrong answer is -2, so wild guessing hurts. This desk recreates that pressure and adds calmer modes so you can build the skill before you race the clock, plus the multiple-choice screen other firms run.

Five ways to train

Ten categories, three difficulties

Questions are generated on the fly, so you never memorize a set: addition and subtraction, multiplication, division, percentages, fractions and decimals, powers and roots, logarithms, and mixed number sense. Difficulty scales from clean two-digit work up to the awkward numbers that separate fast traders from the rest.

The "what comes next?" pattern questions from trading-firm online assessments live on their own desk now, Number Sequences: arithmetic and geometric progressions, second differences, interleaved chains, Fibonacci-style sums, primes and more, like 3, 7, 15, 31, ? They test a different reflex than arithmetic, so they get their own clock.

Try these in your head

23 × 17
391. Difference of squares around 20: 20² − 3² = 400 − 9.
7% of 340
23.8. 10% is 34, so 1% is 3.4; 7% = 34 − 3×3.4 = 34 − 10.2.
Convert 5/8 to a percentage
62.5%. 1/8 = 12.5%, so 5/8 = 5 × 12.5%.
840 ÷ 35
24. 35 × 24 = 35 × 25 − 35 = 875 − 35.

Numeric answers accept a comma or a dot for decimals, and the whole desk is keyboard-first: type, press Enter, move on. Your accuracy per category is tracked so the daily workout can feed extra reps to your two weakest areas.

Explore the rest of the desk