Home  ›  Learning Centre  ›  Maths  ›  Algebra  ›  Writing Expressions
11+ Maths Guide · Year 5–6 · Free lesson

Writing Expressions

'Three more than a number' becomes n + 3 — and once children can translate words to symbols, half of algebra is done. This lesson covers the operation words, the 3n convention and the n − 2 order trap.

A3Writing Expressions
Turn words into algebra.
Expressions describe calculations with letters: n + 5, 3n, n − 2.
Say it in algebra.
5 more than n
n + 5
3 lots of n
3n
2 less than n
n − 2
half of n
n ÷ 2
3n means 3 × n — the multiplication sign hides between number and letter.
1

Learn the 3-Step Method

1Spot the operation words.

‘more than’ → add · ‘less than’ → subtract · ‘lots of / times’ → multiply · ‘shared / half’ → divide.

words → ops

2Write it compactly.

3 × n is written 3n (number first, no × sign). n ÷ 2 can be written n/2.

3 × n = 3n

3Mind the order in subtraction.

‘2 less than n’ is n − 2, NOT 2 − n. Subtraction order matters.

n − 2 ≠ 2 − n
💡 Key IdeaAn expression has no equals sign — it describes a calculation (n + 5). An equation states a fact (n + 5 = 12).
2

Worked Example

Tom is t years old. Write expressions for the family's ages.

His sister is 3 years older
t + 3
His dad is 4 times his age
4t
His cousin is 2 years younger
t − 2
3

Watch Out! Common Mistakes

Writing n3 for 3 lots of n.
n3 ✕ → 3n ✓

Convention! The number always comes first: 3n.

Flipping the subtraction.
“2 less than n” = 2 − n ✕

Order! Start from n and take 2 away: n − 2.

Adding an equals sign.
expression: 3n = ✕

Not yet! An expression just describes the calculation — no equals sign until there’s an equation to state.

Cheat Sheet

WRITING EXPRESSIONS
  1. more than → + · less than → − · lots of → × · shared → ÷
  2. 3 × n is written 3n (number first).
  3. '2 less than n' = n − 2 (order matters).
  4. Expression: no equals sign. Equation: has one.
Example: Tom is t → sister t + 3, dad 4t, cousin t − 2.
📄 Free printable: Download the Writing Expressions cheat sheet (PDF) — keep it by your child's desk.

Quick summary

Frequently asked questions

What does 3n mean?

3 × n — three lots of the unknown number. By convention the number is written first and the multiplication sign is dropped.

What's the difference between an expression and an equation?

An expression describes a calculation with no equals sign (n + 5); an equation says two things are equal (n + 5 = 12) and can be solved.

Why is '2 less than n' written n − 2?

Because you start with n and remove 2. Writing 2 − n calculates something different — the gap below 2, not below n.

← Previous lesson
A2 Function Machines
All lessons
Algebra Hub
Next lesson →
A4 Substitution
🛡️ Curriculum aligned⭐ Builds confidence💜 Made for 9–13 year olds
© MindBlaze. Free to read, share and link to. Learning Centre