Revision GuideGeneral Math

Core Arithmetic Revision Guide

A fuller printable revision guide for core arithmetic, including estimate-first habits, sign checks, place value, and worked examples that support every other calculator on the site.

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Formula highlights

Addition

total = a + b + ...

Division

quotient = dividend / divisor

What this pack covers

Use this guide for the four core operations together with the checking habits that stop sign, decimal, and order mistakes from spreading into later work.

It is designed as a compact revision companion for school maths, technical study, and everyday number work.

Core checks before calculating

Estimate the rough size of the answer first.
Track whether the result should increase, decrease, or stay between familiar bounds.
Line up decimal places when working in written form.
Keep units visible if the numbers represent a real quantity.

Worked examples

14.6 + 3.75 + 0.9 = 19.25, which matches the rough expectation of a little over 19.

7.2 x 0.25 = 1.8 because multiplying by one quarter should quarter the value.

125 / 0.5 = 250 because dividing by a half doubles the number of half-sized pieces.

Common arithmetic traps

Division by numbers less than one often increases the result.
Calculator accuracy does not fix a wrong entry or a wrong operation.
Rounded display values are poor starting points for a second precise calculation.

Best offline use

Keep this sheet nearby when checking finance, engineering, geometry, or percentage work where a small arithmetic slip would create a much larger interpretation error.