What does a child have to do to apply a number code rule in the 11+?

Apply one arithmetic mapping to a letter or number code. It is one of 26 named verbal reasoning skills in the 11+, in the code strand, and this page carries 1 interactive exercise that practises it.

What is the trap in an 11+ apply a number code rule question?

Getting the first letter right does not prove the rule: check it against a second letter of the same word before you trust it. The wrong answers on this skill are built out of that, not out of random numbers, so it is worth naming out loud before your child meets it under time pressure.

What is not part of apply a number code rule in the 11+?

The skill map draws the line here: One invariant rule only. A question past that line is testing a different named verbal reasoning skill, which is worth knowing before you spend a week practising the wrong one.

Which other 11+ skills should we practise alongside apply a number code rule?

The skill map connects it to follow alternating code rules. The alternating-rule task composes repeated single-rule applications. That skill has its own page here.

How can my child practise apply a number code rule for free?

Use Function Machine, embedded on this page. It is the exercise the skill map attaches to apply a number code rule, it runs in the browser with no account to make, these exercises are not scored and do not save learner records. The separate quiz sends answers for marking and shows a score, without saving an assessment record. It also has its own link, so you can send it to a child without sending them anywhere else first.

Verbal Reasoning · Code

Apply a number code rule

Apply one arithmetic mapping to a letter or number code.

Watch the worked example

Crack the Number Code

This video shows how to apply an arithmetic rule to decode letters or numbers in a code. Watch an 11+ verbal reasoning question solved step by step.

Open video page and transcript

Keep practising with Smart Cub Learning. Find topics to practise next

Quick quiz: Apply a number code rule

10 questions, with feedback after each one. No sign-up needed.

Read the questions in this quiz

Question 1
In a code, ALSO is written 27 16 9 13. Using the same rule, how is ROSE written?
- A.8 11 7 21
- B.19 16 20 6
- C.11 14 10 24
- D.10 13 9 23
Question 2
In a code, BOTH is written 25 12 7 19. Using the same rule, how is WOLF written?
- A.5 13 16 22
- B.6 14 17 23
- C.4 12 15 21
- D.3 11 14 20
Question 3
In a code, THIN is written 7 19 18 13. Using the same rule, how is COAT written?
- A.3 15 1 20
- B.24 12 26 7
- C.26 14 28 9
- D.25 13 27 8
Question 4
In a code, BUSH is written 25 6 8 19. Using the same rule, how is PATH written?
- A.11 26 7 19
- B.12 27 8 20
- C.13 28 9 21
- D.16 1 20 8
Question 5
In a code, TALK is written 8 27 16 17. Using the same rule, how is CASH written?
- A.24 26 8 19
- B.25 27 9 20
- C.26 28 10 21
- D.4 2 20 9
Question 6
In a code, WALK is written 4 26 15 16. Using the same rule, how is SPOT written?
- A.7 10 11 6
- B.19 16 15 20
- C.9 12 13 8
- D.8 11 12 7
Question 7
In a code, CASE is written 25 27 9 23. Using the same rule, how is HOUR written?
- A.18 11 5 8
- B.9 16 22 19
- C.21 14 8 11
- D.20 13 7 10
Question 8
In a code, BACK is written 25 26 24 16. Using the same rule, how is LIST written?
- A.12 9 19 20
- B.16 19 9 8
- C.17 20 10 9
- D.15 18 8 7
Question 9
In a code, EACH is written 24 28 26 21. Using the same rule, how is CLUB written?
- A.25 16 7 26
- B.26 17 8 27
- C.5 14 23 4
- D.24 15 6 25
Question 10
In a code, RISK is written 10 19 9 17. Using the same rule, how is SHOE written?
- A.9 20 13 23
- B.20 9 16 6
- C.10 21 14 24
- D.7 18 11 21

Practise it now

Work out which two gears turn these numbers into those numbers.

This exercise practises apply a number code rule alongside its own main skill, Function Machines & Inverse.

Loading the interactive exercise. Nothing you do here is saved or scored.

A worked example

One question of the kind this skill is tested with, worked all the way through: the reasoning, and what the wrong answers are there to catch.

Finding what one letter is worth

In a code, EAR is written 6 2 19. Using the same rule, how is NEW written?

Work one coded word out letter by letter and see why the rule has to be stated before it is used.

13 4 22
14 5 23
16 7 25
15 6 24

Answer: 15 6 24

How you get there

Each letter is worth its place in the alphabet, counting forwards from A, so A is 1, B is 2 and Z is 26 and then adding 1. That is what turns EAR into 6 2 19: E is 6, A is 2, R is 19. Doing the same to NEW gives 15 6 24. "13 4 22" is what you get if you work the rule out from one letter and then apply it slightly differently, which is why the rule is worth writing down as a sentence before you use it on the second word.

Why the other answers tempt

Getting the first letter right does not prove the rule: check it against a second letter of the same word before you trust it.

If they are stuck, say this

Write the alphabet out with 1 to 26 under it, then compare the first letter of the coded word with its number to work out what has been done to it.

Now do it live in Function Machine

Kitchen-table script for parents

Try this together

A friendly mini script for the breakfast table, school run or a quiet two minutes. Read it aloud as written, or make it your own.

Ready? Let's try Apply a number code rule together. Work one coded word out letter by letter and see why the rule has to be stated before it is used. Here comes the question: In a code, EAR is written 6 2 19. Using the same rule, how is NEW written? A handy clue is: Write the alphabet out with 1 to 26 under it, then compare the first letter of the coded word with its number to work out what has been done to it. Nice work. Here is the thinking: "13 4 22" is what you get if you work the rule out from one letter and then apply it slightly differently, which is why the rule is worth writing down as a sentence before you use it on the second word. So our answer is: 15 6 24. One sneaky trap is: Getting the first letter right does not prove the rule: check it against a second letter of the same word before you trust it. Can you show me the first move in your own words? No rush; one calm step is enough.

What this exercise is doing

Function Machine

Work out which two gears turn these numbers into those numbers.

This engine’s own main skill is Function Machines & Inverse. It practises apply a number code rule alongside it.

A function machine does the same thing to every number that enters it. You found the rule backwards, from the outputs, which is inverse thinking. And the order of the gears is part of the rule: ×3 then +1 turns 2 into 7, while +1 then ×3 turns the same 2 into 9. Same gears, different machine.

Step 1. Deduce the gears. Drag gears into the machine so every ticket comes out right.
Step 2. Run it. New number going in. Predict the output BEFORE you pull the lever.

What to say if they get stuck

Look at 2 → 7 and 4 → 13. When the input goes up by 2, the output jumps by 6. What multiplies by 3?
Try ×3 first: 2 becomes 6, but the ticket says 7. What tiny gear finishes the job?
The order of the gears changes the answer. ×3 then +1 gives 7; +1 then ×3 gives 9.

Open Function Machine on its own page to share it

Where apply a number code rule sits in the 11+

The 11+ does not test these skills in isolation, and practising one in the wrong order wastes the practice. These are the skills the curriculum map connects this one to.

This is one piece of: Follow alternating code rules
The alternating-rule task composes repeated single-rule applications.

How apply a number code rule differs from the skills beside it

The same exercise practises several skills, and telling them apart is often the difficulty rather than the exercise itself. On this page the skill is: apply one arithmetic mapping to a letter or number code, and it stops where one invariant rule only.

Evaluate an algebraic expression
Substitute one supplied value and calculate the expression. Excludes solving an equation.
Use a term rule
Use an algebraic rule to calculate a named sequence term. Rule is supplied.

Related verbal reasoning skills

Apply a letter shiftApply one positional alphabet shift, including wrap-around when stated.
Apply mirrored alphabet pairingMap letters through a stated or inferred reversed-alphabet pairing.
Decode a letter-word codeInfer a positional substitution rule and apply it to one new word.

All verbal reasoning 11+ skills

Questions parents ask about apply a number code rule

What this skill involves, common mistakes and ways to practise it at home.

: Apply one arithmetic mapping to a letter or number code. It is one of 26 named verbal reasoning skills in the 11+, in the code strand, and this page carries 1 interactive exercise that practises it.
: Getting the first letter right does not prove the rule: check it against a second letter of the same word before you trust it. The wrong answers on this skill are built out of that, not out of random numbers, so it is worth naming out loud before your child meets it under time pressure.
: Point at the next move rather than explaining the whole rule. Write the alphabet out with 1 to 26 under it, then compare the first letter of the coded word with its number to work out what has been done to it.
: The skill map draws the line here: One invariant rule only. A question past that line is testing a different named verbal reasoning skill, which is worth knowing before you spend a week practising the wrong one.
: The skill map connects it to follow alternating code rules. The alternating-rule task composes repeated single-rule applications. That skill has its own page here.
: Use Function Machine, embedded on this page. It is the exercise the skill map attaches to apply a number code rule, it runs in the browser with no account to make, these exercises are not scored and do not save learner records. The separate quiz sends answers for marking and shows a score, without saving an assessment record. It also has its own link, so you can send it to a child without sending them anywhere else first.

Verbal reasoning is a set of question types, not a subject to revise

A free diagnostic works out which of the codes, analogies, word puzzles and logic types are already secure, and which are not.