A number-sequence item shows a run of numbers governed by a hidden rule — a step, a ratio, an alternating pattern, two interleaved sub-sequences, sometimes a recurrence like Fibonacci — and asks for the next value. You have to infer the rule from limited evidence and apply it, choosing from options that are engineered to look plausible: off-by-one errors, the wrong step, the wrong operation. A half-formed guess usually lands on one of those traps.
Why airlines test it
Sequences are a clean measure of inductive reasoning — your ability to spot an underlying pattern from limited data and predict what comes next. Airlines value it because flying is full of situations where you must build a mental model from partial information and extrapolate, and the test strips that skill down to numbers so it can be measured without any prior knowledge. It also rewards a disciplined, hypothesis-testing mindset over impulsive guessing.
In the cockpit
Recognising a trend early is a survival skill. Is the fuel burn drifting above plan? Is an oil temperature creeping up in a way that will matter in twenty minutes? Is the aircraft's energy converging nicely on the runway, or falling behind the approach? Good pilots continuously project forward — 'if this continues, where will I be?' — and act before a trend becomes a problem. Sequence puzzles train exactly that forward-projection reflex.
For example: on a long sector you jot the fuel remaining overhead each waypoint — 8.2, 7.6, 7.0, 6.4 tonnes — a steady 0.6 t burned per leg. Extend that line in your head to destination and you know now whether you will land above your reserve or need to plan a diversion, long before any low-fuel warning would ever light up. Spotting the pattern and projecting it forward is the entire skill, and here it is measured in numbers instead of fuel.
How to practise
The Number Sequences games below run from Easy to Hard, plus a mixed Full test that mirrors the difficulty of real assessments. Turn the common patterns into instant recognition on the easier sets first, then push into the hard variants, where interleaved and multi-operation rules reward a systematic approach over a hopeful guess. Letter Series applies the same serial induction to the alphabet — a common variation in real batteries, and a good check that you have learned the skill rather than the digits.