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ICT Class 8 - Number System Notes

Comprehensive study notes for Class 8 - Number System olympiad preparation

Number System

Welcome to the chapter on Number System for Class 8. In this chapter, you will learn about different types of number systems, how numbers are represented in computers, and how to convert numbers from one system to another. By the end of this chapter, you will understand binary, decimal, octal, and hexadecimal systems and their importance in ICT!

Introduction

A number system is a way to represent numbers using digits or symbols. Computers use different number systems to store and process data. The most common number systems are decimal, binary, octal, and hexadecimal.

Types of Number Systems

  • Decimal Number System (Base 10): Uses digits 0-9. It is the system we use in daily life.
  • Binary Number System (Base 2): Uses only 0 and 1. It is used by computers.
  • Octal Number System (Base 8): Uses digits 0-7.
  • Hexadecimal Number System (Base 16): Uses digits 0-9 and letters A-F.

Binary Number System

Binary numbers use only two digits: 0 and 1. Each digit is called a bit. Computers use binary to store all information.

  • Example: 1011 (binary) = 11 (decimal)

Octal Number System

Octal numbers use digits from 0 to 7. It is sometimes used in computer programming.

  • Example: 17 (octal) = 15 (decimal)

Hexadecimal Number System

Hexadecimal numbers use digits 0-9 and letters A-F. It is used to represent large numbers in computers.

  • Example: 1A (hexadecimal) = 26 (decimal)

Conversion Between Number Systems

You can convert numbers from one system to another. For example, to convert binary to decimal, multiply each digit by powers of 2 and add them.

  • Binary to Decimal: 101 = 1×22 + 0×21 + 1×20 = 5
  • Decimal to Binary: 7 = 111
  • Hexadecimal to Decimal: 2F = 2×16 + 15 = 47

Why Are Number Systems Important?

  • Computers use binary to store and process data.
  • Hexadecimal is used in programming and web design (like color codes).
  • Understanding number systems helps you work with computers and technology.

Fun Activity: Binary Code Game

Write your name in binary code using 0s and 1s. Find out how computers see your name!

Summary

  • Decimal, binary, octal, and hexadecimal are common number systems.
  • Computers use binary and hexadecimal to store and process information.
  • You can convert numbers between different systems.

Practice Questions

  1. Write the binary form of 6.
  2. Convert 1010 (binary) to decimal.
  3. What is the hexadecimal form of 15?
  4. Write the octal form of 9.
  5. Why do computers use binary numbers?

Challenge Yourself

  • Convert 25 (decimal) to binary and hexadecimal.
  • Find the decimal value of 1101 (binary).

Did You Know?

  • The word "bit" comes from "binary digit".
  • Color codes in computers use hexadecimal numbers.

Glossary

  • Binary: Number system with base 2 (digits 0, 1).
  • Decimal: Number system with base 10 (digits 0-9).
  • Octal: Number system with base 8 (digits 0-7).
  • Hexadecimal: Number system with base 16 (digits 0-9, A-F).
  • Bit: A single binary digit (0 or 1).

Answers to Practice Questions

  1. 110
  2. 10
  3. F
  4. 11
  5. Because computers understand only 0 and 1 (on and off).

Number systems are the language of computers. Practice conversions to become an ICT expert!

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