Deck 01B: Unit 1
Computer Number Systems and Codes
ICT 110: IT for Business
Today's Learning Objectives
By the end of this lecture, you will be able to:
- β
Explain why computers use the binary number system
- β
Identify the four key number systems: Decimal, Binary, Octal, Hexadecimal
- β
Understand basic conversion between number systems
- β
Differentiate between ASCII and Unicode character encoding
- β
Recognize business applications of number systems and codes
Why This Matters for Business
Understanding number systems helps you:
π Storage & Capacity
Understand file sizes, database storage, and bandwidth requirements
π Networking
Grasp IP addresses, MAC addresses, and network configuration
π¨ Web Design
Work with color codes and understand hex values
π³π΅ Nepali Support
Ensure systems can display ΰ€¨ΰ₯ΰ€ͺΰ€Ύΰ€²ΰ₯ correctly
The Computer's Language: Binary
Computers only understand two states: ON (1) and OFF (0)
This is because electronic circuits have two states:
- Current flowing = 1 (ON)
- No current = 0 (OFF)
Everything in a computer β text, images, videos, your eSewa balance β is ultimately stored as patterns of 0s and 1s!
The Four Number Systems
| System |
Base |
Digits Used |
Example |
| Decimal |
10 |
0-9 |
156 |
| Binary |
2 |
0, 1 |
10011100 |
| Octal |
8 |
0-7 |
234 |
| Hexadecimal |
16 |
0-9, A-F |
9C |
All four numbers above represent the same value: 156 in decimal!
Binary: The Foundation
Understanding Bits and Bytes
- Bit: A single 0 or 1 β the smallest unit of data
- Byte: 8 bits grouped together (e.g., 10011100)
- 1 Byte can represent 256 different values (2βΈ)
Storage Units:
1 KB = 1,024 Bytes | 1 MB = 1,024 KB | 1 GB = 1,024 MB | 1 TB = 1,024 GB
Binary to Decimal Conversion
Each position in binary represents a power of 2:
Binary: 1 0 1 1
= (1Γ2Β³) + (0Γ2Β²) + (1Γ2ΒΉ) + (1Γ2β°)
= 8 + 0 + 2 + 1
= 11 in Decimal
Decimal to Binary Conversion
Divide by 2 repeatedly, read remainders from bottom up:
156 Γ· 2 = 78 r 0
78 Γ· 2 = 39 r 0
39 Γ· 2 = 19 r 1
19 Γ· 2 = 9 r 1
9 Γ· 2 = 4 r 1
4 Γ· 2 = 2 r 0
2 Γ· 2 = 1 r 0
1 Γ· 2 = 0 r 1
Result: 156ββ = 10011100β
Hexadecimal: Programmer's Shorthand
Hexadecimal uses 16 symbols: 0-9 and A-F
| A = 10 |
B = 11 |
C = 12 |
D = 13 |
E = 14 |
F = 15 |
Why Hexadecimal?
- 1 hex digit = exactly 4 binary bits
- Much more compact than binary
- Binary: 11111111 β Hex: FF
Where You See Hexadecimal
π¨ Web Colors
#FF5733
This Orange
π MAC Address
00:1A:2B:3C:4D:5E
Network device ID
π IPv6 Address
2001:db8::1
Next-gen internet
Character Encoding: Text as Numbers
Since computers only understand numbers, we need a way to represent letters and symbols as numbers.
- The letter 'A' is stored as the number 65
- In binary: 01000001
- This mapping is called a character encoding standard
ASCII: The Original Standard
American Standard Code for Information Interchange
- Uses 7 bits per character
- Can represent 128 characters
- Includes: A-Z, a-z, 0-9, punctuation, special keys
| Character |
ASCII Value |
| A | 65 |
| a | 97 |
| 0 | 48 |
| Space | 32 |
The Problem with ASCII
ASCII was designed for English only!
It cannot represent:
- ΰ€¨ΰ₯ΰ€ͺΰ€Ύΰ€²ΰ₯ (Nepali/Devanagari)
- δΈζ (Chinese)
- Ψ§ΩΨΉΨ±Ψ¨ΩΨ© (Arabic)
- Emojis ππ
Solution: Unicode!
Unicode: The Universal Standard
- Can represent 143,000+ characters
- Covers 154 writing scripts
- Includes Devanagari, emojis, ancient scripts, and more
UTF-8 is the most common encoding:
Uses 1-4 bytes per character (efficient for English, flexible for others)
Unicode Examples
| Character |
Code Point |
Description |
| A |
U+0041 |
Latin Capital A |
| ΰ€ |
U+0915 |
Devanagari KA |
| ΰ€¨ΰ₯ΰ€ͺΰ€Ύΰ€² |
Multiple |
"Nepal" in Devanagari |
| π |
U+1F600 |
Grinning Face Emoji |
Why Unicode Matters for Nepal
π¦ Banking
Customer names in ΰ€¨ΰ₯ΰ€ͺΰ€Ύΰ€²ΰ₯
Currency symbol: ΰ€°ΰ₯
ποΈ Government
Nagarik App
e-Passport system
π³ eSewa/Khalti
Display "ΰ€°ΰ₯ 5,000"
Nepali interface
π E-commerce
Daraz, SastoDeal
Product descriptions
Business Application: SMS Limits
English SMS: 160 characters (ASCII)
Nepali SMS: 70 characters (Unicode)
Why the difference?
- ASCII uses 7 bits per character
- Unicode uses 16 bits for Devanagari
- Same total bits = fewer characters!
Marketing teams must consider this when planning Nepali SMS campaigns!
Quick Reference: Storage Units
| Unit |
Size |
Can Store Approximately |
| 1 Byte |
8 bits |
1 English character |
| 1 KB |
1,024 bytes |
Half a page of text |
| 1 MB |
1,024 KB |
1 minute of MP3 audio |
| 1 GB |
1,024 MB |
~250 songs or 1 HD movie |
| 1 TB |
1,024 GB |
~500 hours of video |
Key Takeaways
- Computers work in binary because circuits have two states (ON/OFF)
- Hexadecimal is a compact way to represent binary (used in colors, addresses)
- ASCII encodes English characters; Unicode supports all languages
- UTF-8 is the modern standard for text encoding
- Understanding these concepts helps in IT decision-making across all business functions
Review Questions
- Why do computers use binary instead of decimal?
- Convert binary 1101 to decimal.
- What color system uses #FF5733 format?
- Why is Unicode important for Nepali businesses?
- Why can a Nepali SMS only have 70 characters vs 160 for English?
Thank You!
Questions?
ICT 110: IT for Business