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Fast arithmetic drills built to prepare candidates for timed numerical assessments at market making and proprietary trading firms.
Solve as many operations as possible before the timer runs out. Used by Jane Street, Optiver, and Citadel candidates.
Market makers like Optiver, Jane Street, Flow Traders, Akuna Capital, and SIG evaluate mental arithmetic speed not because traders perform arithmetic by hand in production, but because rapid numerical reflex correlates with:
Multiply the tens digit $n$ by $(n+1)$, then append $25$.
Sum the digits and place the result between the original digits.
Turn nearby multiplication into $a^2 - d^2$.
Memorize fractional baselines to compute fast yield swings.