Fiducia TogetherEstimation
Rounding to easy numbers to check whether an answer is sensible.
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
Estimation rounds each value to 1 significant figure and calculates with those, giving an approximate answer used as a check.
Where it applies
Both tiers, and it is a marked skill in its own right.
How it works
Its purpose is catching errors of magnitude — the answer that is ten times too big because of a misplaced decimal point.
Questions also ask whether an estimate is an over- or under-estimate, which depends on the direction each value was rounded.
How to use it in your work
Show the rounded values before calculating. That is where the mark is.
For over/under-estimate questions, reason about each rounding: rounding the denominator down makes the answer bigger.
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.