Number sequences test practice for trading interviews

Optiver, IMC and Flow Traders all run a "what comes next?" section in their online assessment, separate from the arithmetic one. It rewards a different reflex: you are not calculating, you are hunting for a rule under a clock. This desk generates 26 pattern families across three tiers, and when you miss one it tells you the rule you did not see. Free, in your browser.

How to read a sequence fast

Almost every sequence in these tests falls out of a short checklist, run in order. Most candidates lose time because they try to see the answer instead of working the checklist.

1. Take the gaps. Constant gap means add a fixed number. If the gaps themselves grow by a constant, you have a quadratic (triangular numbers, squares plus a shift).
2. Take the ratios. A constant ratio is geometric. A ratio that alternates between two values is an alternating-ratio pattern.
3. Try "each term from the previous ones". Sum of the two before it (Fibonacci), sum of the three before it (tribonacci), product of the two before it, or a mix like 3x + 1.
4. Look for two interleaved chains. If nothing works on consecutive terms, check terms 1, 3, 5 against terms 2, 4, 6.
5. Check the number families. Squares, cubes, fourth powers, primes, prime squares, and running sums of primes or of squares.

Try these

Three tiers, 26 families

• Warm-up: constant differences and ratios, squares, alternating adds.
• Interview: growing gaps and drops, multiply-then-add, Fibonacci style, products of neighbours, cubes, two-term recurrences, tribonacci, alternating ratios.
• Ruthless: interleaved chains, rational ratios, primes, alternating operations, square steps, rising multipliers, products of the two previous terms, fourth powers, prime squares, square gaps and prime gaps.

Questions are generated on the fly, so there is no set to memorize, and every family is built so the terms on screen pin the rule down: there is exactly one sensible continuation. Run it untimed to learn the checklist, or on a clock (1, 2 or 5 minutes) to reproduce the assessment.

Four options or free typing, your call

Most assessments show you four candidates, so that is the default here. The wrong ones are not random: they are the terms a misread rule produces, the number you land on if you keep the last gap when the gaps are actually growing, if you keep the last ratio when the rule is additive, or if you apply the rule to the wrong term. Eliminating them is a skill, which is the point.

Switch the answer mode to Type it and the options disappear. Harder, because nothing can be recovered by elimination, and worth doing once the checklist is second nature.

Each run ends with your accuracy broken down by pattern type, so you find out that you are fine on ratios and blind to interleaved chains, plus a review of every sequence you missed with its rule written out in plain language.

Explore the rest of the desk

Based on public interview reports and candidate accounts; formats change, so verify the current process with your recruiter. My Quant Journey is independent: not affiliated with, sponsored by or endorsed by any trading firm.