What number comes next in this series? 2, 9, 16, 23, 30, ___
Show worked explanation
The pattern is +7 each time. 30 + 7 = 37. Tip: Check the gap between the first two numbers, then verify it works for all pairs. ✓
11+ Number Series Practice
(GL Assessment)
Number series sit right at the meeting point of maths and reasoning. Your child is shown a run of numbers, usually five to seven of them, such as 3, 7, 11, 15, 19, and has to work out the rule and give the number that comes next. The skill is not arithmetic for its own sake. It is spotting the hidden relationship between the numbers, whether that is a steady step, a times table, growing gaps or something more inventive.
Number series are a dependable feature of the GL Assessment 11+ Verbal Reasoning paper. Our research estimate is roughly 3 to 5 questions per paper, with the missing number almost always at the end of the run. The numbers are whole numbers; decimals and fractions are essentially absent and negatives are rare. Your child chooses from five options (A to E) and marks the answer on a separate sheet, so quick, accurate pattern-spotting matters as much as the maths itself.
On this page your child practises these sequences one at a time, building the instinct to write down the gaps between numbers and read the pattern from there. Every question has a worked explanation that names the rule and shows the final step, so your child learns to verify the answer against the whole series rather than trusting the first idea.
What the GL 11+ Tests on Number Series
Number series are built from a wide range of patterns. GL does not publish how often each appears, so this order is our research estimate, grouped roughly from most approachable to most demanding:
- Constant addition or subtraction (the same amount is added or taken away each step, such as +4 or -7): the most common and most reliable pattern
- Times tables and multiples (the numbers count up in a familiar table, such as 6, 12, 18, 24): quick to spot once the tables are secure
- Doubling and halving (each number is twice or half the one before): a frequent middle-difficulty pattern
- Increasing or decreasing differences (the gap itself grows or shrinks, such as +2, +3, +4, +5): the step up from constant patterns
- Square, cube and other special numbers (1, 4, 9, 16, 25 or 1, 8, 27, 64), and prime numbers (2, 3, 5, 7, 11): rewards recognising known sequences
- Fibonacci-style rules (each number is the sum of the two before it) and triangular numbers (1, 3, 6, 10, 15): patterns hidden in the relationships
- Interleaved and compound rules (two patterns woven together, or a rule such as times two then add one): the hardest type to unpick
Difficulty rises from a single constant gap on small numbers, through growing differences, squares and doubling, up to interleaved sequences where odd and even positions follow different rules and answers can occasionally be negative.
Sample Number Series Questions
Five questions drawn from PrepStep’s number series bank, spanning Foundation to Challenging. Tap “Show worked explanation” to see the full method after you’ve had a go. The correct answer is highlighted on each question so you can check immediately.
What number comes next in this series? 5, 10, 17, 26, 37, ___
Show worked explanation
Differences: +5, +7, +9, +11. They increase by 2 (odd numbers). Next: +13. 37 + 13 = 50. Tip: Differences increasing by 2 means the gaps are consecutive odd or even numbers. ✓
What number comes next in this series? 1, 3, 7, 13, 21, ___
Show worked explanation
Differences: +2, +4, +6, +8. They increase by 2 (even numbers). Next: +10. 21 + 10 = 31. Tip: When differences increase by 2, the next difference is the last one plus 2. ✓
What number comes next in this series? 27, 37, 29, 39, 31, ___
Show worked explanation
Odd positions: 27, 29, 31 (+2). Even positions: 37, 39, 41 (+2). Next is even: 41. Tip: If the sequence bounces around, ALWAYS try splitting into odd and even positions! ✓
What number comes next in this series? 50, 45, 40, 35, 30, ___
Show worked explanation
The pattern is -5 each time. 30 - 5 = 25. Tip: Descending sequences subtract the same amount each time. ✓
Common Mistakes to Avoid
Common mistake 1 of 4
Writing the gap instead of the next number.
Tip: After finding that the series goes up by 7, it is easy to write 7 rather than the actual next term. Remind your child that the gap is a clue, not the answer, and that the final step is to add (or subtract) that gap to the last number shown.
Common mistake 2 of 4
Assuming a steady gap when the gaps are growing.
Tip: Some series add a little more each step, so a child who spots the first gap and stops there gets caught. Teach your child to write the gap under every pair of numbers, then check whether those gaps are constant or changing before deciding the rule.
Common mistake 3 of 4
Missing an interleaved pattern.
Tip: When a series looks chaotic, it is often two patterns woven together, with the odd positions following one rule and the even positions another. Encourage your child to split the series into alternate numbers and look at each strand separately before giving up.
Common mistake 4 of 4
Slipping on the arithmetic with larger numbers.
Tip: Off-by-one and simple addition errors are common, and GL builds wrong options that sit one or two away from the correct number. The fix is to work the final calculation carefully on paper and confirm the rule fits every number in the run.
Frequently Asked Questions
What is a number series in the GL 11+ exam?
It is a Verbal Reasoning question that shows a run of numbers, usually five to seven of them, with the last one missing. Your child works out the rule linking the numbers, such as adding the same amount each time or following a times table, and chooses the number that comes next from five options (A to E). The missing number is almost always at the end of the series.
How many number series questions are in the GL paper?
Our research estimate is around 3 to 5 number series questions in a typical GL Assessment 11+ Verbal Reasoning paper, since GL does not publish exact counts. They use whole numbers, with decimals and fractions essentially absent and negative answers rare, so the focus is firmly on spotting the pattern quickly and adding up accurately.
How do you work out a number series pattern?
The most reliable method is to write the difference between each pair of numbers. If the differences are all the same, it is a constant add or subtract. If the differences themselves form a pattern, the gaps are growing or shrinking. If the series still looks random, try splitting it into alternate numbers, since two patterns may be woven together. Always check your rule works for every number shown.
What are the hardest number series questions?
The toughest are interleaved sequences, where odd and even positions follow different rules, and compound rules such as times two then add one. Cube numbers and doubling differences are also demanding. These reward children who can recognise known sequences like squares, cubes, primes and Fibonacci, and who check the rule against the whole series rather than just the last two numbers.
How can my child get better at number series?
Secure times tables, quick recall of square and cube numbers, and the habit of writing down the gaps all make a big difference. Free PrepStep practice gives your child these sequences one at a time with worked explanations that name the rule and show the final step, so the pattern-spotting becomes faster and more confident with each attempt.
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