A number series question is among the shortest tests an employer can give. One row of numbers, one blank, four options. It is easy to administer and easy to score, which explains why it turns up in screening. It does not explain what a score means, and that is worth being clear about.
What the employer is looking at
A series question samples one thing: can the candidate find a rule in a short run of numbers and apply it. That touches pattern recognition, quick mental arithmetic and care in checking, and almost nothing else.
It does not sample teamwork, domain knowledge, communication or the judgement a role needs when no rule is available. Employers who use it well use it as one signal in a set, never as the whole picture.
What the research says, and what it does not
Reasoning tests as a family have a long history in selection research. Schmidt and Hunter (1998) is a widely cited review that compared selection methods across 85 years of findings, and it is the usual starting point for the case that cognitive-style tests are useful in hiring.
The case is about general reasoning tests, assessed carefully, for appropriate roles. It is not a blanket endorsement of any particular short test, and it does not tell you how a candidate will do in your particular job.
A note on the JobCannon test
The JobCannon Number Series test is an in-house tool: its questions are original to JobCannon, and it has no published norms and no reliability or validity study. It gives each person a score, a band and a breakdown by kind of rule, which is useful for self-knowledge and practice. It should not be used as a hiring cut-off.
That limitation is why this article does not quote any population averages, pass marks or percentiles for the test: there are none to quote.
Fairness and preparation
- Familiarity helps, so ask which test will be used and whether an example is available.
- Time pressure can disadvantage people who reason well but slowly; where an employer can offer extra time, they should.
- Use more than one signal. A short numerical check beside an interview and a work sample is stronger than any of the three alone.
- Do not over-read a single score. A candidate who has seen the format has an advantage unrelated to the job.
Questions worth asking before the test
- Which test will it be, and is there an example I can try beforehand?
- How long is it, and is the timer per question or for the whole paper?
- Are calculators or scrap paper allowed?
- Do wrong answers lose marks, or only score zero?
- How is the result used: a cut-off, or one input among several?
Employers who answer these clearly are usually the ones using the test sensibly. Vague answers are worth noting too.
If you are the candidate
Learn the seven common rule types, practise the gap-and-ratio routine and rehearse under a timer. The number series practice page and the JobCannon Number Series test are free practice; the blog's pieces on finding the rule and on time per question cover method and pacing.
If the employer's test turns out to cover tables, percentages and charts as well, the JobCannon Numerical Reasoning test is the closer practice. An employer's numerical test may combine both kinds of item.