Number Series
Spotting the rule behind a numeric sequence — differences, ratios, times-n-plus-k, squares and cubes with an offset, alternating and second-level patterns — to find a missing term or the term that breaks the rule.
What you will be able to do
- Check a sequence against the common patterns in a fixed order.
- Use the first and second differences to identify a pattern.
- Tell a missing-term question from a wrong-term question and solve each.
- Confirm a rule against every gap before committing to an answer.
What is inside this lesson
- 1What the question tests
- 2The patterns to check, in order
- 3Missing term versus wrong term
- 4Reading the pattern from the gaps
- 5Worked examples
- 6Common mistakes
- 7Quick revision
- 8Practice
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What the question tests
A number series question gives a sequence built by one hidden rule and asks for a term. Two versions appear: find the missing term, shown as a blank or a question mark, and find the wrong term, where every number is printed but one does not fit the rule.
The skill is pattern recognition under time pressure, not heavy calculation. A rule is almost always one of a short list, so you check that list in order rather than staring at the numbers. This topic is about numeric patterns; the letter and reasoning versions sit in the reasoning section.
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