# [Python] Binary & Decimal Number Systems and how to convert between them

Photo by Mika Baumeister on Unsplash

## Table of contents

# Introduction

The binary and decimal number systems are important concepts in Mathematics, Computer Science and Digital electronics. And in almost all programming languages, we have some functions which help us convert numbers from one system to the other and vice versa. Python is no different. We have a few ways in which we can achieve this. Let us explore them.

# Binary to decimal

We can use the `int()`

function with two arguments, first the **string representation** of the binary number and the second argument is the base, in this case 2.

Example:

```
n = '01100110'
print(f"The decimal representation of {n} is {int(n, 2)}")
```

will output

```
The decimal representation of 01100110 is 102
```

# Decimal to binary

Python has the `bin()`

function which takes in a decimal integer and returns a string representation of its binary form

This string is preceded by '0b' which can be removed by the `replace()`

method

Example:

```
m = 18
print(f"{m} in binary is {bin(m).replace('0b', '')}")
```

this will print

```
18 in binary is 10010
```

We can also convert decimal to binary with the help of a **format specifier**, like

```
p = 4
print('{0:b}'.format(p))
```

will print `100`

That is it for this article. Hope you found this helpful. Please share your thoughts in the comments below.