# Data Representation / Numbering Conversion / File Permissions

### Main Objectives of this Practice Tutorial

• Understand the importance of how computers store data (i.e. data representation)
• Understand the purpose of decimal, binary, octal and hexadecimal numbers
• Perform various numbering conversions between the decimal, binary, octal and hexadecimal numbering systems
by hand without the use of a computer or calculator
• Identify which numbering system conversion method to use when required to perform a numbering conversion
• Understand directory and regular file permissions
• Learn how to set directory and regular file permissions with the chmod command (symbolic and octal methods)
• Learn how to use the umask command to have permissions for directories and files automatically set upon their creation

### Tutorial Reference Material

 Course Notes Numbering Conversion / File Permissions Reference YouTube Videos Course Notes:PDF | PPTX Data Representation Definition Decimal, Binary, Octal, Hexadecimal Numbers Numbering Conversion Binary to Decimal / Decimal to Binary Binary to Octal / Octal to Binary Binary to Hexadecimal / Hexadecimal to Binary Octal to Hexadecimal / Hexadecimal to Octal File Permissions chmod umask Instructional Videos:x x x x

### Why Study Data Representation?

Computers process and store information in binary format For many aspects of programming and networking, the details of data representation must be understood

C Programming – sending information over networks, files Unix / Linux – setting permissions for files and directories Web Pages – setting color codes

In terms of this course, we will learn how a simple decimal number (integer) is stored into the computer system as a binary number.

We will also learn other numbering systems (octal and hexadecimal) that can be used as a "short-cut" to represent binary numbers.

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