Number is a core part of GCSE Maths. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Place valueThe value of a digit depends on its position.
Integers & negativesWhole numbers including negatives; rules for + − × ÷.
Primes & factorsPrime numbers, factors, multiples, HCF and LCM.
Order of operationsBIDMAS: brackets, indices, division/multiplication, addition/subtraction.
Rounding & estimationRounding to decimal places or significant figures.
Standard formWriting very large or small numbers as A × 10ⁿ.
PrimeWhole number > 1 with only 1 and itself as factors
FactorA whole number that divides exactly into another
MultipleResult of multiplying a number by a whole number
HCFHighest Common Factor — biggest factor shared by both
LCMLowest Common Multiple — smallest shared multiple
Square rootNumber that multiplied by itself gives the original
IndexThe power: in 2³ the 3 is the index
BaseThe number being raised: in 2³ the 2 is the base
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What is the value of x^0 (for x not equal to zero)?✗ x^0 equals 0 because raising something to the zero gives nothing. ✓ 1 — any non-zero number to the power of zero equals 1.
What does x^(1/2) mean?✗ x^(1/2) means x divided by 2 — half of x. ✓ The square root of x (the positive root when x is positive).
Fully factorise 6x + 9.✗ 3(2x + 9), by only dividing the first term by the common factor. ✓ 3(2x + 3) — take out the common factor 3.
Does multiplying always make a number bigger?✗ Yes, multiplication always increases a number. ✓ No — multiplying by a number between 0 and 1 makes it smaller.
How do you decide the order of operations?✗ Always strictly left to right. ✓ Brackets, indices, then ×/÷, then +/− (BIDMAS).
Practise Number — free games
Test yourself with these quick revision games for this topic:
See all 17 games in the Subjects Arcade →
More GCSE Maths topics
← All revision guides
Want to revise every topic this smart?
The Velvet Method teaches you to use AI to revise any subject — £25, lifetime access.
Explore the Course →