📘 Chapter 2: Formulas and Functions in Excel

Abbreviation Full Form

SUM Sum (Function – adds numbers)
AVG / AVERAGE Average (Function – mean of numbers)
MIN Minimum (Function – smallest value)
MAX Maximum (Function – largest value)
IF If Statement (Conditional Function)
COUNT Count (Function – counts numbers)
PEMDAS Parentheses, Exponents, Multiplication, Division, Addition, Subtraction
BODMAS Brackets, Orders, Division, Multiplication, Addition, Subtraction
Ctrl Control (Keyboard key for shortcuts)

🌐 Chapter 7: Networks

Abbreviation Full Form

PAN Personal Area Network
LAN Local Area Network
CAN Campus Area Network
MAN Metropolitan Area Network
WAN Wide Area Network
NIC Network Interface Card
IP Internet Protocol
ISP Internet Service Provider
Wi-Fi Wireless Fidelity
URL Uniform Resource Locator
HTTP HyperText Transfer Protocol
HTTPS HyperText Transfer Protocol Secure
FTP File Transfer Protocol
SMTP Simple Mail Transfer Protocol
IMAP Internet Message Access Protocol
P2P Peer-to-Peer
HTML HyperText Markup Language
DNS Domain Name System
USB Universal Serial Bus (often used in PANs)
DSL Digital Subscriber Line (for internet access)

📘 Chapter 2: Formulas and Functions in Excel

🧮 1. What Is a Spreadsheet?

A spreadsheet is a digital tool (like Microsoft Excel) that organizes data in rows and columns, which intersect to form cells.

 Cell: A single box where you can enter data. Identified by its cell address (e.g., A1, B3).
 Workbook: A file that contains one or more worksheets.
 Worksheet: A single spreadsheet tab inside a workbook.

🧾 2. What Is a Formula?

A formula is an expression that calculates the value of a cell. It always begins with an equals sign =.

✅ Example:

=A1 + B1
This adds the values of cells A1 and B1.

🎯 Purpose:

 To perform arithmetic calculations (add, subtract, multiply, divide).

 To dynamically update results when cell values change.

➗ 3. Arithmetic Operators in Excel

Operator Meaning Example

+ Addition =A1 + A2
- Subtraction =B1 - B2
* Multiplication =C1 * 5
/ Division =D1 / 2
^ Exponent =A1 ^ 2

🧠 4. Order of Operations

Excel follows PEMDAS or BODMAS rules:

Parentheses
Exponents (Power)
Multiplication / Division
Addition / Subtraction

📌 Example:

=2 + 3 * 4 → Result: 14 (not 20)

=(2 + 3) * 4 → Result: 20

📌 5. Types of Cell References

🔁 Relative Reference:

 Changes when formula is copied to another cell.

 Example: =A1 + B1 becomes =A2 + B2 when dragged down.

📌 Absolute Reference:

 Fixed; doesn’t change when copied.

 Use $ to lock column and/or row.
 Example: =$A$1 + B1 → A1 stays constant.

🔄 Mixed Reference:

 Either row or column is fixed.

 Examples:
o =$A1: Column A is fixed
o =A$1: Row 1 is fixed

🔧 6. Common Excel Functions

Functions are predefined formulas that simplify calculations.

 Function Purpose Syntax Example
SUM Adds values =SUM(A1:A5) Adds A1 to A5
AVERAGE Calculates mean =AVERAGE(B1:B5) Average of B1 to B5
MIN Smallest value =MIN(C1:C5) Minimum of C1 to C5
MAX Largest value =MAX(D1:D5) Maximum of D1 to D5
COUNT Counts numeric values =COUNT(E1:E10) Counts numbers only
IF Conditional logic =IF(F1>50,"Pass","Fail") Returns Pass/Fail

🧠 7. The IF Function (In Detail)

Syntax:

=IF(condition, value_if_true, value_if_false)

Example:

=IF(A1>=40, "Pass", "Fail")

 If A1 is 40 or more, result is “Pass”; otherwise, “Fail”.

You can also nest IFs:

=IF(A1>=90, "A+", IF(A1>=75, "A", "B"))

🧩 8. Creating and Copying Formulas

 Use the fill handle (small square at cell corner) to drag formulas across rows/columns.
 Excel automatically adjusts relative references but not absolute ones.

🔄 9. AutoFill & Series

 AutoFill can continue sequences: e.g., 1, 2, 3… or Jan, Feb, Mar…

 Also applies to formulas for quick copying.

⚠ 10. Errors in Formulas

Error Code Meaning Example

#DIV/0! Division by zero =A1/0
#NAME? Misspelled function or range =SUUM(A1:A5)
#REF! Invalid cell reference Deleting a referenced cell
#VALUE! Wrong data type Text used in number formula

📊 11. Formula Bar and Name Box

 Formula Bar: Shows content of selected cell (can be formula or value).

 Name Box: Shows current cell’s address (e.g., A1) or defined range name.

🧪 12. Practice Example

Spreadsheet:
 A B
40 60
80 20
70 90

Sample Formula in C1:

=AVERAGE(A1:B1)

Result: 50

🧠 Summary of Key Skills:

 Use correct operators and function syntax.

 Understand how to fix or shift references.
 Apply logic using IF statements.
 Troubleshoot error messages.
 Use AutoFill to save time.

📘 1. What is a Computer Network?

 Definition: A computer network is a collection of two or more devices (computers, printers, mobile devices) connected by wired
or wireless links to share resources and information (scribd.com).
 Purpose & Functions:
o Enables communication: email, messaging, file transfer.
o Facilitates sharing of hardware (printers, scanners), software, and storage.
o Centralized backups and database access (anyflip.com, fliphtml5.com).

2. 🛠 Components of a Network

 Sender / Receiver: Devices that transmit or receive data (edurev.in).

 Transmission Medium: The physical (cables) or wireless channels for data transfer.
 Protocols: Rule sets enabling communication between devices—e.g. TCP/IP, HTTP, POP3, IMAP (fliphtml5.com).
 Devices:
o Hub: Shares incoming signal with all ports.
o Switch: Forward packets to the correct destination only.
o Router: Connects different networks; directs packets between them .
o Gateway: Bridges networks with different protocols .
o Modem, Repeater, NIC (Ethernet card), Access Point .

3. 📏 Types of Networks (By Coverage)

 LAN (Local Area Network): Covers small geographical areas like a building or campus. High speed (~1000 Mbps), privately
owned (anyflip.com).
 MAN (Metropolitan Area Network): Connects multiple LANs across a city or town (scribd.com).
 WAN (Wide Area Network): Spans broad regions, like countries or continents (anyflip.com).
 (Personal Area Network—often optional in Grade 8 content.)

4. 🔄 Network Topologies
  Star topology: All nodes connect to a central hub/switch. Easy to expand; single node failure doesn't halt network. If central
device fails, entire network goes down (fliphtml5.com, fliphtml5.com).
 Bus topology: Nodes share a single cable (trunk). Simple and cost-effective; cable failure affects entire network (fliphtml5.com).
 Ring topology: Devices form a closed loop; data passes sequentially. Node failure disrupts transmission (fliphtml5.com).

5. 📶 Transmission Media

 Wired media:
o Twisted-pair cable: Common in LANs.
o Coaxial cable: Used for older network systems or cable TV (fliphtml5.com).
 Wireless media: Wi-Fi, Bluetooth, mobile (3G/4G/5G)—provide mobility but face challenges like collisions and interference .

6. 🔐 Packet Switching & Protocols

 Packet switching: Data divided into packets sent via different paths; reassembled at destination .
 Protocols:
o TCP/IP: Foundation of internet data transmission.
o HTTP: For web browsing.
o IMAP/POP3: Email retrieval/storage protocols (fliphtml5.com).
o FTP, etc.

7. ⚙️Network Architectures

 Client–Server: Central server provides resources to multiple client PCs.

 Peer-to-Peer: Equal devices share resources without central server .

8. ✅ Advantages & Disadvantages

Advantages:

 Resource sharing (printers, software).

 Cost-effective, centralized backups.
 Efficient communication and collaboration (fliphtml5.com).

Disadvantages:

 Single point of failure (e.g. hub crash).

 Security risks if not managed properly.
 Cable or device breakdown affects operations.

9. 📚 Important Definitions

Term Definition

Protocol Rules for communicating in a network

Topology Layout structure of network devices

LAN / MAN / WAN Networks classified by size

Hub, Switch, Router, Gateway, Repeater Core network hardware

 Term Definition

Packet Switching Data splitting into packets for transmission

Client / Server / Peer-to-Peer Types of network architecture