# Definition:Binary Notation

## Definition

Binary notation is the technique of expressing numbers in base $2$.

That is, every number $x \in \R$ is expressed in the form:

$\ds x = \sum_{j \mathop \in \Z} r_j 2^j$

where $\forall j \in \Z: r_j \in \set {0, 1}$.

## Examples

### $23$ in Binary Notation

The number written in decimal notation as $23$ is expressed in binary notation as $10111_2$.

### $36$ in Binary Notation

The number written in decimal notation as $36$ is expressed in binary notation as $100100_2$.

### $47$ in Binary Notation

The number written in decimal notation as $47$ is expressed in binary notation as $101111_2$.

### $68$ in Binary Notation

The number written in decimal notation as $68$ is expressed in binary notation as $1000100_2$.

### $127$ in Binary Notation

The number written in decimal notation as $127$ is expressed in binary notation as $1111111_2$.

## Also see

Binary notation, like hexadecimal notation, has particular relevance in the field of computer science.

## Historical Note

The earliest known reference to binary notation appears to be in a Chinese book dating from approximately $3000$ B.C.E.

In Europe, binary notation was invented by Gottfried Wilhelm von Leibniz.

He associated God with $1$ and nothingness with $0$, and believed that it was mystically significant that all numbers could be built from $1$-ness and $0$-ness.