Fiducia TogetherSignificant figures
The digits in a number that carry meaning. How exam questions usually want answers rounded.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Significant figures count from the first non-zero digit. In 0.004508, the significant figures are 4, 5, 0 and 8 — so to 2 s.f. it is 0.0045.
Decimal places count from the decimal point instead, which is a different instruction.
Where it applies
Every maths paper and every science calculation question.
How it works
Rounding to a sensible number of significant figures signals the precision you actually have. An answer of 3.333333 from data measured to 2 s.f. claims accuracy nobody has.
Zeros between digits always count; leading zeros never do; trailing zeros after a decimal point do.
How to use it in your work
Read the instruction. "3 significant figures" and "3 decimal places" give different answers and questions specify one.
Round at the END. Rounding partway through and then continuing is a reliable way to lose the accuracy mark.
If a question does not say, giving 3 s.f. is normally safe.
Where to get help
Your teacher, your board's specification for what is on your paper, and Bitesize for worked examples. The maths song runs the topics in order.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Maths Song The GCSE maths topics, in order.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.