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 two calmer modes so you can build the skill before you race the clock.

Three ways to train

Eleven 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.

There is also a dedicated number sequences category, the "what comes next?" pattern questions from trading-firm online assessments: arithmetic and geometric progressions, second differences, interleaved chains, Fibonacci-style sums, primes and more, like 3, 7, 15, 31, ? Spot the rule, type the next term.

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