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Verbal reasoning letter codes: a step-by-step guide

Updated 2026-11-14

Letter codes are one of the most common verbal reasoning question types. They look puzzling at first, but nearly all of them follow a few patterns, and a written alphabet makes them much easier.

Write the alphabet first

Many tests allow rough working or print the alphabet on the page. Writing A to Z across the top with the letters numbered 1 to 26 underneath turns code questions into simple counting. It is worth practising until it takes under a minute.

Type 1: every letter moves the same amount

If CAT is written as DBU, what is the code for DOG?

C to D, A to B and T to U are all one place forward. So D becomes E, O becomes P and G becomes H. The answer is EPH.

Always check every letter. Some codes move each letter by a different amount, such as +1, +2, +3.

Type 2: mirror codes

In a mirror code, each letter swaps with the letter the same distance from the other end of the alphabet: A with Z, B with Y, C with X, and so on. A quick check is that each pair adds up to 27 when you number the letters (A = 1, Z = 26).

Using a mirror code, BAD becomes YZW.

The alphabet A to Z numbered 1 to 26, with arrows showing C to D, A to B and T to U. Shift +1: CAT → DBU, so DOG → EPH. Mirror code: BAD → YZW. — Writing the alphabet with numbers turns code questions into counting.

Type 3: decode a word

Some questions work backwards: given the code, find the word. Reverse the rule. If the code moves letters two places forward, move them two places back to decode. Then check that your answer is a real word, which is a good sign that the rule is right.

Practice tips

Start untimed, writing every step, then speed up.
Watch the ends of the alphabet: moving one place forward from Z goes back to A.
If the first letter fits a rule but the second does not, try a different rule rather than forcing it.

Questions parents ask

Do all 11+ tests include letter codes?

No. Verbal reasoning question types vary between tests, and some tests do not include verbal reasoning at all. Check a sample paper for your child's test.

Can my child write the alphabet on the paper?

In most tests children can use rough paper or the margins, but rules vary, so check the instructions for your test.

How long should a code question take?

With practice, most children can answer a simple code question in under a minute.

Want to see what a paper set out like your child's test looks like? Every pack and handbook has a free sample. Find your test area or try the free flash cards.