# How many Bytes in… In this challenge we will write a set of functions to calculate how many Bytes there are in a given number of kilobytes, megabytes, gigabytes, terabytes or petabytes.

First let’s investigate the link between these storage units: BytesKilobytesMegabytesGigabytesTerabytesPetabytes
A Byte is a small storage unit that contains 8 bits. Here is what a Byte looks like:

01101110

A Byte can be used to store an integer between 0 and 255, or a single character (using the ASCII code).
A kilobyte (KB) contains 1024 Bytes.
1 KB = 1024 Bytes

A text file is often measured in Kilobytes as it would contain a few thousand characters.
A megabyte (MB) contains 1024 kilobytes.
1 MB = 1024 KB
= 1024 x 1024 Bytes

A digital photograph or an mp3 would typically take up a few megabytes of disk space.
A gigabyte (GB) contains 1024 megabytes.
1 GB = 1024 MB
= 1024 x 1024 KB
= 1024 x 1024 x 1024 Bytes

A high quality movie (DVD) would take up a few gigabytes. An SD card or USB key would contain a few GB of data.
A terabyte (TB) contains 1024 gigabytes.
1 TB = 1024 GB
= 1024 x 1024 MB
= 1024 x 1024 x 1024 KB
= 1024 x 1024 x 1024 x 1024 Bytes

A hard drive can contain a few Terabytes of data.
A petabyte (PB) contains 1024 terabytes.
1 PB = 1024 TB
= 1024 x 1024 GB
= 1024 x 1024 x 1024 MB
= 1024 x 1024 x 1024 x 1024 KB
= 1024 x 1024 x 1024 x 1024 x 1024 Bytes

Very large databases stored on web servers used by large websites (Google, Facebook, etc…) will contain a few Petabytes of data.

#### Subroutines?

By completing this challenge we will investigate how subroutines (functions/procedures) are used in Python to create sections of code that can be called/reused many times within a program. Subroutines mean that a section of code can be identified using a name (identifier). This enables us to add more instructions to the already existing functions used in Python such as print or input.

To create a new function in Python we have to declare it first using the keyword def in Python. Our first function will be called kilobytes_to_bytes() and will take one parameter: numberOfKilobytes: (integer value).

We will then add the code to calculate the number of bytes that this function should return:

Note how the code for the subroutine/function is indented to the right.

We will then be able to call our the kilobytes_to_bytes() function to perform any conversion. T

Check the Python code below where we have implemented and used the kilobytes_to_bytes() function to convert a user input into bytes.

• megabytes_to_bytes()
• gigabytes_to_bytes()
• terabytes_to_bytes()
• petabytes_to_bytes() Create a new Python program that will:

• Ask the user how old they are (age in years),
• Convert this number in days knowing that there are 365.25 days in a year,
• Output this number of days to the end-user. 