number system is the way we name and represent numbers. The number system we use in our daily life is known as decimal number system or base 10 because it is based on 10 different digits: 0, 1, 2, ..., 8, and 9. The base of number is written as subscript to a number. For example, the decimal number "twelve thousand three hundred and forty-five" is written as 1234510. Without a base or explicit context, it's assumed that a number is in base 10.

In computer science, apart from the decimal system, three additional number systems are commonly used: binary (base-2), octal (base-8), and hexadecimal or just hex (base-16). Binary numbers are important because that is how numbers are stored in the computer. Octal and hexadecimal are used to represent binary numbers in a user-friendly way. Each octal symbol represents 3 binary bits and each hex digit represents 4 binary bits. For example, the decimal number 53201, stored as in the computer as the binary number 10000001111000101100, is represented by the octal number 2017054, and the hex number 81E2C. The table below compares the number systems:


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  1. Introduction
Converting between Decimal, Binary and Octal
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  1. Anatomy introduction
  2. Binary to decimal
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  1. Flexibility introduction
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