Letter sequences are solved by writing the alphabet down the side of your page and counting the gaps. Almost every mistake children make on these comes from trying to do the counting in their head.
It helps to split verbal reasoning the way you would split mathematics, into applied topics and language topics. The applied ones have a rule. Teach the rule, practise it, and a child improves quickly. The language ones, anagrams and antonyms and the rest, rest on reading and cannot be taught around.
This is an applied type, which is good news: it is one of the fastest places to pick up marks.
The method, in four steps
- Write out the alphabet at the top of the paper, once, at the start of the section. Number it if that helps: A is 1, Z is 26.
- Mark the gaps between each term, not between each letter. Write the number of steps above the arrows.
- Look for a pattern in those gaps, not in the letters.
- Apply the gap forward and check your answer against the options.
A worked example
Find the next pair: CE, GI, KM, OQ, ?
Treat each pair as two separate jobs.
| Pair | First letter | Second letter | Gap inside the pair |
|---|---|---|---|
| CE | C (3) | E (5) | +2 |
| GI | G (7) | I (9) | +2 |
| KM | K (11) | M (13) | +2 |
| OQ | O (15) | Q (17) | +2 |
Inside each pair the gap is +2 every time. Between the pairs, the first letters run 3, 7, 11, 15, so they go up by 4. Next first letter is 19, which is S, and the second is 21, which is U.
The answer is SU.
The pattern most children miss
Some sequences do not move forward at all. They mirror.
AZ, BY, CX, DW, ?
The first letters go forward one at a time. The second letters go backward one at a time. Another way to see it: each pair adds to 27. A (1) plus Z (26) is 27. B (2) plus Y (25) is 27.
So the next pair is E (5) with V (22), because 5 plus 22 is 27. The answer is EV.
If a sequence looks like nonsense, check for mirroring before anything else. It is the single most common hidden rule in this question type.
The rules worth knowing by sight
| Pattern | What it looks like |
|---|---|
| Constant step | A, C, E, G: always +2 |
| Growing step | A, B, D, G: +1, +2, +3 |
| Two interleaved sequences | Odd positions follow one rule, even positions another |
| Mirror | Letter pairs that sum to 27 |
| Backward | The whole thing runs in reverse. Check direction first |
Where the marks actually go
- Counting in the head. Write the alphabet. It takes fifteen seconds once and saves minutes.
- Forgetting to wrap. After Z you go back to A. Children lose whole questions to this.
- Looking at letters instead of gaps. The pattern is almost never in the letters themselves.
- Not checking the direction. Confirm the sequence is going forward before you start.
Work through the partnership's familiarisation questions to see the exact answer format, and see our guide to verbal reasoning for how this fits the rest of the paper.
See where your child stands today
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This is one of the quick wins. Treat it as one
I find it useful to split verbal reasoning the way you would split mathematics, into applied topics and language topics. Letter sequences sit squarely in the applied family, along with codes, coded calculations and finding a word hidden inside another.
These are genuinely easy to teach. There is a rule, the rule can be shown in one session, and once a child has it they improve fast. If a child is struggling here, the gap is almost never the method. It is usually that nobody has shown them the rule at all.
So do not let this type eat your preparation time. Teach it properly, drill it until it is automatic, bank the marks, and put the hours you save into reading, because that is what moves the language types and those are where the real spread of marks sits.
Mushtaque Ahmed, Founder of GrammarPath and Bright Mentors
Frequently asked questions
How do you solve 11+ letter sequence questions?
Write the alphabet out at the top of the page, number it if it helps, then mark the gaps between each term rather than studying the letters themselves. The pattern is almost always in the size of the steps. Apply that step forward and check against the options.
What is the trick for letter sequences like AZ, BY, CX?
They mirror. The first letters move forward while the second letters move backward, and each pair sums to 27 using A equals 1 and Z equals 26. So after DW comes EV, because E is 5, V is 22 and they total 27.
Why does my child keep getting letter sequences wrong?
Usually because they are counting in their head rather than writing the alphabet down, or because they forget that sequences wrap around from Z back to A. Both are habits rather than understanding, and both are fixed quickly.
Are letter sequences hard to learn for the 11+?
No, and this is one of the fastest places to gain marks. Letter sequences are an applied question type: there is a rule, the rule can be taught in a single session, and children improve rapidly once they have a reliable method.
What letter sequence patterns come up in the 11+?
Constant steps such as A, C, E, G; growing steps such as A, B, D, G; two interleaved sequences where odd and even positions follow different rules; mirror pairs summing to 27; and sequences running backwards. Checking the direction first saves a lot of wasted time.