Unit 2: Operating System & MS Office
Chapter 7: Number System & Data Representation
English Definition: A number system represents numbers using a defined base and set of symbols.
Hinglish Explanation: Computer internally binary use karta hai because digital circuits commonly work with two states: 0 and 1.
- Binary base 2: 0,1.
- Octal base 8: 0–7.
- Decimal base 10: 0–9.
- Hexadecimal base 16: 0–9 and A–F.
- 1 byte = 8 bits.
- ASCII represents characters using codes; Unicode supports a much wider range of scripts and symbols.
| System | Base | Digits |
|---|---|---|
| Binary | 2 | 0–1 |
| Octal | 8 | 0–7 |
| Decimal | 10 | 0–9 |
| Hexadecimal | 16 | 0–9, A–F |
Chapter 8: Operating Systems
English Definition: An operating system is system software that manages hardware, software resources, files and user interaction.
Hinglish Explanation: Operating System computer aur user/applications ke beech bridge ka kaam karta hai.
- Functions: process management, memory management, file management, device management, security and user interface.
- Examples: Windows, Linux, macOS, Android, iOS.
- GUI uses graphical elements; CLI uses text commands.
- Booting means starting the computer and loading the operating system.
- Multitasking allows multiple tasks/processes to be handled concurrently.
| OS function | What it does |
|---|---|
| Process management | Runs/schedules processes |
| Memory management | Allocates memory |
| File management | Organizes files/folders |
| Device management | Controls peripherals |
| Security | Access/authentication controls |
Chapter 9: Windows & File Management
- File extension often indicates file type: .docx, .xlsx, .pptx, .pdf, .jpg, .mp3, .exe.
- Recycle Bin temporarily holds many deleted files.
- Copy duplicates; Cut + Paste moves.
- Compression reduces file size; ZIP is a common archive format.
Shortcut Trick:
Ctrl + C (Copy)
Ctrl + X (Cut - X looks like scissors)
Ctrl + V (Paste - V looks like an arrow inserting something)
Ctrl + C (Copy)
Ctrl + X (Cut - X looks like scissors)
Ctrl + V (Paste - V looks like an arrow inserting something)
| Action | Common shortcut |
|---|---|
| Copy | Ctrl + C |
| Cut | Ctrl + X |
| Paste | Ctrl + V |
| Rename | F2 |
| Permanent delete | Shift + Delete |
Chapter 10: MS Word
Hinglish Explanation: Word documents banane, formatting, tables, headers, footers, mail merge aur printing ke liye use hota hai.
- Common features: font formatting, paragraph alignment, styles, tables, headers/footers, page numbers.
- Mail Merge creates personalized documents for multiple recipients.
- Spell Check helps identify spelling/grammar issues.
- Track Changes records edits.
- Common extensions: .docx; older .doc.
Chapter 11: MS Excel
- Workbook contains worksheets; a cell is identified by column letter + row number (e.g., A1).
- Formula begins with =.
- Functions: SUM, AVERAGE, COUNT, MAX, MIN, IF.
- Relative reference changes when copied; absolute reference uses $ such as $A$1.
Excel Calculation Flow
| Function | Purpose | Example |
|---|---|---|
| SUM | Total | =SUM(A1:A10) |
| AVERAGE | Mean | =AVERAGE(A1:A10) |
| COUNT | Count numbers | =COUNT(A1:A10) |
| MAX | Largest | =MAX(A1:A10) |
Chapter 12: MS PowerPoint
- Presentation consists of slides. Common extension: .pptx.
- Transitions occur between slides; animations affect objects on a slide.
- Slide Master controls consistent design/layout.
- F5 starts slide show from beginning in many desktop versions.
📝 SSC Practice MCQs (Unit 2)
SSC CGL
Q1. Which number system has base 2?
Answer: C. Binary
Solution: Binary number system has base 2 (0 and 1). Decimal has 10, Octal has 8, Hexadecimal has 16.
Solution: Binary number system has base 2 (0 and 1). Decimal has 10, Octal has 8, Hexadecimal has 16.
SSC CHSL
Q2. In Excel, a formula normally starts with:
Answer: B. =
Solution: Every formula in Microsoft Excel must begin with an equals sign (=).
Solution: Every formula in Microsoft Excel must begin with an equals sign (=).
SSC MTS
Q3. Which key combination copies selected content?
Answer: B. Ctrl+C
Solution: Ctrl+C is used to copy. Ctrl+X is cut, Ctrl+V is paste, Ctrl+P is print.
Solution: Ctrl+C is used to copy. Ctrl+X is cut, Ctrl+V is paste, Ctrl+P is print.
SSC CPO
Q4. Which Excel function returns the largest value?
Answer: B. MAX
Solution: The MAX function returns the largest numeric value in a range of values.
Solution: The MAX function returns the largest numeric value in a range of values.