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Memory exercise · ~2 min a run · free

Reverse Digit Span

Hold the last few digits of a stream, then say them backwards.

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Digits arrive one at a time, spoken aloud and shown on screen, and you are not told how many are coming. When the stream stops, you recall the last few in reverse order, most recent first. Each level you clear adds a digit to the span. It combines holding a moving window of a running stream with a backward-recall transformation, the working-memory load a pilot carries when reading back a clearance while still flying.

About this test

What this test measures

This measures backward working memory over a running stream: how many recent digits you can hold from an unannounced-length sequence and then reorder in reverse. It layers a manipulate-while-holding demand on top of simple recall, which is the load a pilot carries when reading back a clearance while still flying the aircraft.

How to improve your score

  • Hold only a rolling tail of the last few digits, dropping the oldest as each new one arrives, instead of trying to keep the whole stream.
  • Rehearse the window in a steady rhythm during the stream so it does not fade before it stops.
  • Practise with the audio on where you can, since holding a spoken sequence is the channel the real task loads.

Good to know

  • Technique: rehearse a rolling tail

    Do not try to hold the whole stream. Keep only the last few digits alive, and as each new digit lands, drop the oldest and add the new one to the end of your mental list. When the stream stops you already hold the window; then read it out from the newest backwards.
  • What good looks like

    In our testing, a typical adult reaches a reverse span of around 4 or 5 digits, and steady practice can push it higher. As a rough guide, aim to add a digit to your best span every few sessions rather than expecting a large jump at once.

Frequently asked questions

How is this different from the number memory exercise?

Number memory shows a fixed-length number and asks you to repeat it forwards. Reverse Digit Span presents a running stream of unannounced length and asks for the last few digits backwards. It adds two demands: tracking a moving window, and reordering it in reverse, which is a harder manipulation than simple repetition.

Why present the digits as audio?

Much of a pilot's memory load is auditory, holding a spoken clearance or frequency. Practising with audio trains the same channel. The digits are also shown on screen so the exercise works with the sound off and on mobile, and so it is accessible.

Is this a specific published test?

No. Reverse Digit Span is an original SkyStudy exercise. Backward digit span is a long-established memory paradigm in the public domain; this implementation is not affiliated with, licensed by, or derived from any specific test publisher or airline.

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