1.3 - Octal Number System
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Octal System
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today, we will explore the Octal Number System, which is based on 8 and uses the digits from 0 to 7. Can anyone tell me why octal is used in computing?
Isn't it because it makes binary numbers shorter?
Exactly! Each octal digit represents three binary digits. This compactness helps simplify binary representations. For example, the binary '110' can be represented as '6' in octal.
So, how do we convert octal numbers to decimal?
Great question! To convert octal to decimal, we multiply each digit by the power of 8 based on its position. Let's take the number 345₈ as an example.
Conversion from Octal to Decimal
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
As we mentioned, let's convert 345₈ to decimal. Who can tell me what we do first?
Multiply the first digit by 8 squared, then the second by 8 to the power of one, and the last digit by 8 to the power of zero?
Correct! And what do we get?
192 for the 3, then 32 for the 4, and 5 for the last digit, making it 229₁₀!
Perfect! Recap that process: 3 times 64 plus 4 times 8 plus 5. Remember this pattern for other octal numbers!
Converting Decimal back to Octal
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now let’s focus on converting a decimal number into octal. How would we tackle the number 229₁₀?
We divide by 8 and track the remainders!
Exactly! Let's perform the divisions together!
229 divided by 8 is 28 with a remainder of 5. Then 28 divided by 8 is 3 with a remainder of 4, and finally, 3 divided by 8 gives us 0 with a remainder of 3!
Well done! Reading the remainders from bottom to top gives us 345₈. This is a key skill you will need!
Application in Computing
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
What are some applications you can think of for octal numbers in computing?
Maybe in file permissions in UNIX systems?
That's correct! Octal is used to simplify the representation of permission settings. We often express permissions like '775' in UNIX, where each digit corresponds to a different category!
Cool! So, learning this system is useful for programming too!
Exactly, understanding these conversions is foundational for anyone wishing to work in programming or computer science!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
In the Octal Number System, which functions on a base-8 principle, numbers consist of the digits 0 through 7. This system allows for a more compact representation of binary numbers, as one octal digit corresponds to three binary digits. Conversion processes between octal and decimal are crucial for applications in computing.
Detailed
Octal Number System
The Octal Number System is a numeral system that operates on a base-8 foundation, incorporating eight digits: 0, 1, 2, 3, 4, 5, 6, and 7. This system plays a vital role in computing, particularly as it provides a more compact representation of binary numbers; each octal digit directly corresponds to a triplet of binary digits (bits). For example, the octal number 345 can be expressed in binary as 110101101.
Converting Between Number Systems
- Octal to Decimal: To convert an octal number to decimal, each digit is multiplied by the power of 8 corresponding to its position:
- Example: Convert 345₈ to decimal: 3 × 8² + 4 × 8¹ + 5 × 8⁰ = 192 + 32 + 5 = 229₁₀
- Decimal to Octal: Conversion from decimal to octal involves successive division by 8 while keeping track of the remainders:
-
Example: Convert 229 to octal:
229 ÷ 8 = 28 remainder 5,
28 ÷ 8 = 3 remainder 4,
3 ÷ 8 = 0 remainder 3, Hence, read the remainders from bottom to top, giving the octal representation 345₈.
Importance in Computing
The octal system is particularly useful in simplifying binary numbers for easier reading and writing. Understanding the conversion between octal and decimal is essential for programming and working with digital electronics.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
What is Octal?
Chapter 1 of 3
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
The Octal Number System is a base-8 system, meaning it uses eight digits: 0 to 7. It provides a more compact representation of binary numbers, where each octal digit represents three binary digits (bits).
Detailed Explanation
The octal number system is a numeral system that uses 8 symbols: 0, 1, 2, 3, 4, 5, 6, and 7. This system is especially useful in computing because it offers a more concise way to express binary values. In fact, every single octal digit corresponds to three binary digits (bits). This means that instead of writing out a long binary number, you can use fewer digits in octal to represent the same value. For example, the binary number 101010 can be represented as the octal number 52, as 101 in binary translates to 5 in octal and 010 translates to 2.
Examples & Analogies
Imagine you are packing for a trip and need to label your luggage. Instead of writing out a long phrase to describe each suitcase, you choose a number on a simple label as a code. For example, '4' could represent a suitcase with clothes, '3' could represent shoes, etc. Using these simple numbers makes it easier and faster to recognize what you have packed, just as octal simplifies binary representation in computing.
Converting Octal to Decimal
Chapter 2 of 3
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Octal numbers can be converted to decimal by expanding the octal number using powers of 8:
Example: Convert 345_8 to decimal.
3458=3×82+4×81+5×80=192+32+5=229_{10}
Detailed Explanation
To convert an octal number to decimal, you expand it by expressing each octal digit as a power of 8. The rightmost digit represents 8^0, the next represents 8^1, and so on. For example, in the octal number 345, you can break it down as follows:
- The '3' is in the 8^2 place, which equals 3 × 64 = 192.
- The '4' is in the 8^1 place, which equals 4 × 8 = 32.
- The '5' is in the 8^0 place, which equals 5 × 1 = 5.
Then, you sum these results: 192 + 32 + 5 = 229 in decimal.
Examples & Analogies
Think of converting octal to decimal like figuring out the total points scored in a game by different players. Each player represents digits of an octal number, and their contributions are weighted by where they are sitting (their position in the number). Just like you would multiply each player's score by a factor based on their position to get the total team score, you multiply each octal digit by 8 raised to the power of its position and sum them to get the decimal value.
Converting Decimal to Octal
Chapter 3 of 3
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Decimal numbers can be converted to octal using successive division by 8, noting the remainders.
Example: Convert decimal number 229 to octal.
229÷8=28 remainder 5
28÷8=3 remainder 4
3÷8=0 remainder 3
Reading the remainders from bottom to top gives 345_8.
Detailed Explanation
To convert a decimal number to octal, you repeatedly divide the decimal number by 8 and keep track of the remainder at each step. For the number 229, when you divide by 8, you get a quotient and a remainder. You keep dividing the quotient by 8 until it reaches zero. The remainders then tell you the digits of the octal number, read in reverse order. For 229, you divide: 229 ÷ 8 = 28 with a remainder of 5; 28 ÷ 8 = 3 with a remainder of 4; 3 ÷ 8 = 0 with a remainder of 3. Hence, the octal representation is read as 345.
Examples & Analogies
Imagine you're collecting stones and organizing them. Each time you fill a bag with 8 stones, you note how many bags you filled and how many stones are left over (the remainder). You keep track of how many bags you filled until you can’t fill any more. When you look back at your collection, you see how many bags (octal digits) you have and note the extra stones you have (remainders). Just like this allows you to keep your stones organized, converting decimal to octal organizes the numbers into a more manageable system.
Key Concepts
-
Octal Number System: A numeral system based on 8 using digits 0 through 7.
-
Base-8 Conversion: The method of changing a number from octal to decimal or vice versa.
-
Binary Representation: How octal condenses binary data, where one octal digit represents three binary digits.
Examples & Applications
To convert 345₈ to decimal, calculate 3x8² + 4x8¹ + 5x8⁰ = 229₁₀.
To convert 229₁₀ to octal, divide by 8 and track the remainders: 229 ÷ 8 = 28 remainder 5 gives you the final octal number 345₈.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Octal's eight, it's simply great, 0 to 7, it can calculate!
Stories
Imagine a group of eight friends named 0 to 7 form a tight team to build binary rockets that shoot up high, revealing the world of computing!
Memory Tools
For octal digits remember: 'Old (0,1) Cats (2,3) Have (4,5) Seven (6,7) Lives!'
Acronyms
Remember OCT for Octal, converting to decimal
Octal's Conversion Tricks!
Flash Cards
Glossary
- Octal Number System
A base-8 numeral system that uses digits from 0 to 7.
- Base8
A numeral system where each digit represents a power of 8.
- Conversion
The process of changing a number from one numeral system to another.
Reference links
Supplementary resources to enhance your learning experience.