Arithmetic is the foundational branch of mathematics dealing with numbers and the basic operations performed on them—addition, subtraction, multiplication, and division. It underpins virtually all quantitative reasoning, from everyday calculations like budgeting and measurement to advanced fields such as algebra, calculus, and computer science. Understanding arithmetic means grasping positional notation, properties of operations, and number classification — including the hierarchy from natural numbers through rational and irrational to real numbers — which together form the mental framework that makes all higher mathematics accessible and intuitive.
What This Cheat Sheet Covers
This topic spans 21 focused tables and 162 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
A jump-to index of every table row in this cheat sheet.
An interactive map of every table and concept in this topic.
Table 1: Basic Operations
The four operations that everything else here is built from. Addition and multiplication each come with an inverse — subtraction and division — and seeing them as paired opposites makes the rest of arithmetic far easier to reason about.
| Operation | Example | Description |
|---|---|---|
5 + 3 = 8 | • Combines two or more numbers into a sum • the fundamental operation for counting forward. | |
9 - 4 = 5 | • Finds the difference between two numbers • the inverse of addition. |