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Number System in Computer Organization: Its Types with Examples

11 Nov 2025
6 min read

Key Takeaways From the Blog

  • Computers use number systems to represent, process, and store all forms of data.
  • The four main types of number systems are:
    • Binary (Base 2): Used internally by all computer hardware.
    • Octal (Base 8): A compact form of binary representation.
    • Decimal (Base 10): Human-readable numeric system.
    • Hexadecimal​‍​‌‍​‍‌​‍​‌‍​‍‌ (Base 16): It is mainly utilized in programming and memory addressing. 
    • Character encoding systems such as ASCII, Unicode, and ISCII take numeric representation further by representing text and symbols for worldwide compatibility.
  • The changes of systems (binary ↔ decimal ↔ octal ↔ hexadecimal) are necessary for programming, debugging, and data reading. 
  • Number systems are instrumental in the implementation of various functions, including data representation, arithmetic operations, memory addressing, input/output (I/O) processing, and error detection. 
  • Knowing number systems thoroughly is an essential step towards understanding computer organization, digital electronics, and software ​‍​‌‍​‍‌​‍​‌‍​‍‌development.

Introduction

In computer organization, the number systems are important for allowing the computer to process, store, and communicate data. Computers represent data with decimal numbers with certain number systems. Knowing what these systems are will help you understand how computers operate the way they do and process data efficiently. Below is a detailed description of each number system and how it relates to computer organization.

What is Number System in Computers?

A number system is a way of expressing numbers in a consistent manner using digits or other symbols. In the context of computers, a number system represents data and performs operations at the machine level. Computers typically work with binary, octal, decimal, and hexadecimal systems. These systems serve as the foundation for data encoding, arithmetic operations, and other computations in computers.

Types of Number Systems in Computer Organization

There are 4 types of number systems in computer organization:

1. Binary Number System

The binary number system is the most fundamental system used in computers. It uses only two digits, 0 and 1, to represent all data. This is because the underlying electronic circuits in a computer can only understand two states on (1) and off (0). Every bit in binary can represent a single binary digit, making it the building block for all computer operations.

25 24 23 22 21 20

Example: 

For 11010,

= 1 × 2⁴ + 1 × 2³ + 0 × 2² + 1 × 2¹ + 0 × 2⁰ 

= 16 + 8 + 0 + 2 + 0

= (26)10

2. Octal Number System

The octal number system is a base-8 system that uses digits from 0 to 7. It is used as a shorthand representation of binary numbers because each octal digit corresponds to a group of three binary digits (bits).

85 84 83 82 81 80

Example: 

For 726,

=7 × 8² + 2 × 8¹ + 6 × 8⁰ 

= 7 × 64 + 2 × 8 + 6

= 448 + 16 + 6 = (470)10

3. Decimal Number System

The decimal number system is used in everyday life, based on base 10. It uses digits from 0 to 9. Although computers don't natively use the decimal system, it is important for human-computer interaction, as users generally interact with computers using decimal numbers.

105 104 103 102 101 100

Example: 

In 720, the value of 7 is 700 (7 × 10²), the value of 2 is 20 (2 × 10¹), and the value of 0 is 0 (0 × 10⁰).

4. Hexadecimal Number System

The hexadecimal number system is a base-16 system that uses digits from 0 to 9 and letters A to F (representing values 10 to 15). It is commonly used in computer programming to represent binary data, as each hexadecimal digit corresponds to four binary digits.

165 164 163 162 161 160

Example: 

For number 27FB:

2 × 16³ + 7 × 16² + 15 × 16¹ + 11 × 16⁰ 

= 2 x 4096 + 7 x256 + 15 x 16 + 11

= 8192 + 1792 + 240 + 11

= (10235)10

5. ASCII (American Standard Code for Information Interchange)

ASCII is a 7-bit character set encoding standard for representing English letters, numbers, and symbols within computers with numeric values. ASCII converts characters into binary codes for storage and processing.

Example: 'A' = 65 → Binary: 01000001

6. Unicode

Unicode is a platform-independent character encoding scheme that can be utilized to represent text in any language and script. It gives a code point to every character, which makes the data represent uniformly on any platform.

Example: 'अ' = U+0905 → Binary (UTF-16): 0000100100000101

7. ISCII (Indian Script Code for Information Interchange)

ISCII is an 8-bit encoding scheme developed to represent Indian scripts such as Devanagari or Tamil or Bengali. All Indian language characters are encoded together in one binary format that is common to all. 

Example: 'अ' = Code 161 → Binary: 10100001

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Conversion of the Number System in Computer Organization

One of the most essential skills in computer organization is converting numbers from one system to another. Since computers use different number systems—such as the binary number system, octal numbers, decimal, and the hexadecimal number system—understanding these conversions is crucial for data processing, storage, and binary logic compatibility.

1. Decimal to Binary Conversion

To convert a decimal number to binary, repeatedly divide the decimal number by 2, recording the remainder each time. The binary representation is formed by reading the remainders in reverse order (from last to first).

Example:
Convert decimal 25 to binary:

  1. 25 ÷ 2 = 12, remainder 1
  2. 12 ÷ 2 = 6, remainder 0
  3. 6 ÷ 2 = 3, remainder 0
  4. 3 ÷ 2 = 1, remainder 1
  5. 1 ÷ 2 = 0, remainder 1
    Read the remainders upward: 11001

This process highlights the importance of place value in the binary number system.

2. Binary to Decimal Conversion

To convert a binary number to decimal, multiply each bit by 2 raised to the power of its position (starting from 0 on the right), then sum the results.

Example:
Convert binary 1011 to decimal:
= 1 × 2³ + 0 × 2² + 1 × 2¹ + 1 × 2⁰
= 8 + 0 + 2 + 1
= 11

3. Decimal to Hexadecimal Conversion

For decimal to hexadecimal conversion, divide the decimal number by 16, keeping track of the remainders. Use digits 0-9 and letters A-F (where A=10, B=11, …, F=15) for values above 9.

Example:
Convert decimal 254 to hexadecimal:

  1. 254 ÷ 16 = 15, remainder 14 (E)
  2. 15 ÷ 16 = 0, remainder 15 (F)
    Read the remainders upward: FE

4. Hexadecimal to Binary Conversion

Each hexadecimal digit directly maps to a 4-bit binary sequence. Replace each digit with its binary equivalent.

Example:
Hexadecimal 2F:
2 = 0010, F = 1111
So, 2F = 00101111 in binary.

5. Binary to Octal Conversion

Group the binary digits into sets of three (starting from the right) and convert each group to its octal equivalent.

Example:
Binary 1100101:
Groups: 1 100 101
1 = 1, 100 = 4, 101 = 5
So, 1100101 = 145 in octal numbers.

6. Octal to Decimal Conversion

Multiply each octal digit by 8 raised to the power of its position (starting from 0 on the right), then sum the results.

Example:
Octal 207:
= 2 × 8² + 0 × 8¹ + 7 × 8⁰
= 128 + 0 + 7
= 135 in decimal.

BCD (Binary Coded Decimal) Conversion

BCD stands for a method in which every decimal digit is represented by a separate binary code. This method makes the number more human-readable and also simplifies the decimal display on digital devices. As an example, the decimal number 59 in BCD is 0101 1001.

Complexity in Conversion and Learning Curve

Working with different number systems can be confusing and may take some time to understand, especially if you are a beginner. Errors are typically made due to incorrect placing of the remainders or because the person making the conversion doesn't quite understand the value of the place. On top of that, binary and hexadecimal numbers are sometimes difficult for people to read and understand without converting them into decimal first, which adds to the complexity of conversion and decreases human readability.

Quick Recap

  • Knowing how to convert between different systems is a fundamental computing skill necessary for working with data.
  • Binary ↔ Decimal ↔ Octal ↔ Hexadecimal conversions are place values and remainders-based operations.
  • Being conversion accurate is the key to error-free data processing and smooth hardware-software ​‍​‌‍​‍‌​‍​‌‍​‍‌interaction. 

Importance of Number Systems in Computer Organization

The importance of number systems in computers cannot be overstated. Number systems form the core of all computer operations and have a direct impact on several key areas:

  • Number systems are used to represent various types of data in computers, such as integers, floating-point numbers, and characters.
  • The ability to perform operations with binary or hexadecimal numbers allows computers to perform fast arithmetic calculations.
  • Number systems influence how data is stored in memory. For example, binary representation is used in RAM and hard drive storage, while hexadecimal representation is commonly used for memory addresses.
  • Programming languages often require the use of different number systems to manage and manipulate data effectively, especially for low-level system programming or hardware interaction.

Representation of Number System in Computer Organization

The numbers are represented in binary, octal, decimal, and hexadecimal in the below table:

Binary Octal Decimal Hexadecimal
0000 0 0 0
0001 1 1 1
0010 2 2 2
0011 3 3 3
0100 4 4 4
0101 5 5 5
0110 6 6 6
0111 7 7 7
1000 10 8 8
1001 11 9 9
1010 12 10 A
1011 13 11 B
1100 14 12 C
1101 15 13 D
1110 16 14 E
1111 17 15 F

Advantages of Number System in Computer Organization

Here are the advantages of the number system in computer organization:

  • Number systems can help convert one number system to another.
  • Using binary or hexadecimal numbers allows computers to process data and perform calculations more quickly and efficiently.
  • The binary number system is simple to use, with only two digits, 0 and 1.

Disadvantages of Number System in Computer Organization

Here are the disadvantages of the number system in computer organization:

  • Hexadecimal numbers are difficult to read and write, and complex mathematical operations like multiplication and division can be difficult to perform.
  • The decimal number system is less suitable for specific applications
  • Binary and octal numbers are not easily understandable for humans, requiring conversion to and from more familiar decimal or hexadecimal systems.

Applications of Number Systems in Computer Organization

Number systems have been used in computer organization in their various aspects. They have been the means for the representation, processing, and communication of data, keeping the whole process accurate, as well as the designing of digital systems efficient.

1. Data Representation

Number​‍​‌‍​‍‌​‍​‌‍​‍‌ systems are the essential ways through which information is encoded in computers. Any numbers or characters can be represented with the use of binary, octal, hexadecimal, or ASCII/Unicode, which is what makes it possible for machines to store, process, and exchange data in a more accurate and efficient manner. 

2. Arithmetic Operations

Computer devices are capable of executing addition, subtraction, multiplication, and division using binary and other number systems. By using logic circuits, these operations are realised in hardware; thus, the performance of these operations is high-speed, precise, and reliable in all computational tasks.

3. Memory Addressing

Number systems serve the purpose of giving the unique address to different parts of memory. The use of the hexadecimal numbering system simplifies the long binary addresses so that it is easier for programmers to reference, read, debug, and manipulate data stored in computer memory.

4. Input/Output Systems

Without the help of number systems, computers would find it very hard to interact with the outside world. The usage of decimal and hexadecimal representations has become the standard in devices like displays, keyboards, and debugging tools, through which users are enabled to enter data and make sense of the given outputs.

5. Data Transmission

The main objective of using a binary code and a character encoding system like ASCII or Unicode is to ensure that data transfers would be stable and unbroken between two devices. Number systems play a very important role as the communicators' standardizers as they eliminate the sources of errors in interactions and allow computers to interpret, process, and display information correctly.

6. Error Detection and Correction

Numbers systems are the means to the generation of error-detecting and error-correcting codes, for instance, parity bits, checksums, and CRC. These codes support the identification and correction of errors in transmission or storage, thus, the continuation of data integrity in digital systems. 

7. Digital Electronics & Software Development

Number systems are the basis logic design, hardware realization, and software creation need. Engineers and programmers can use base conversions, binary logic, and encoding to efficiently and accurately produce digital hardware and software solutions.

Key Takeaways so far:

  • Number systems (binary, octal, decimal, hexadecimal, ASCII, Unicode, ISCII) are at the core of how computers store, process, and communicate data.
  • The pros are computation speed, conversion ease, and hardware-friendly representation; the cons are readability and human interpretability problems.
  • The scope of applications is the same as technology is covering: data representation, arithmetic operations, memory addressing, input/output systems, error detection, and digital system design.
  • Expertise in number systems is instrumental for programming, debugging, and getting hardware and software operations in ​‍​‌‍​‍‌​‍​‌‍​‍‌computers. 

Conclusion

In conclusion, the number systems are the core of the computer to run and hold data. They give the method for machines to read and work with numbers effectively. Whether binary, hexadecimal, octal, or decimal, however the system may be, it is necessary to learn these systems for computer organization students or computer program students.

Why It Matters?

Understanding number systems is crucial because it reveals how computers interpret and process data. It bridges the gap between human-readable numbers and machine logic, showing how data moves through processors and memory. Mastering number systems builds the foundation for programming, debugging, and digital design—helping you think like a computer and strengthen both technical and analytical skills.

Practical Advice for Learners

  • Start with basics: Practice binary and decimal conversions manually to build a strong foundation.
  • Use visual aids: Tables and charts help connect binary, octal, decimal, and hexadecimal relationships.
  • Apply concepts in context: Explore real-world applications—such as memory addressing, color codes in HTML (hex), and ASCII tables—to reinforce learning.
  • Integrate into practice: Use number system knowledge in programming tasks, logic circuit design, and microprocessor studies to develop hands-on expertise.

Frequently Asked Questions

1. What are the four types of number systems? 

The four main types of number systems used in computer organization are:

  • Binary (base 2)
  • Octal (base 8)
  • Decimal (base 10)
  • Hexadecimal (base 16)

2. What is the application of the number system? 

The application of number systems in computers is crucial for data representation, computation, memory management, and interaction with hardware. Different number systems help optimize storage, increase the speed of operations, and make data more manageable in programming.

3. What is the use of a number system in computers? 

The use of a number system by computers is to communicate, store, and compute information so that electronic circuits and processors can interpret. Hexadecimal, binary, and other systems are extremely significant to perform calculations, storage in memory, and communication with software programs. They are basic to basic mathematics to complex algorithms in contemporary computing.

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