DEV Community: Isaac Mageto

EXCEL : INTRODUCTION AND FUNDAMENTALS OF EXCEL.

Isaac Mageto — Mon, 31 Aug 2026 19:13:22 +0000

Excel is one of the most commonly used tools for working with data.

You can use it to enter information, organize it, format it, clean it, perform calculations, and identify patterns.

In this guide, we'll use a simple sales dataset to learn the fundamentals.

NB : I have used a made up dataset in my analysis.

Understanding Excel

An Excel file is called a workbook.

A workbook contains worksheets.

A worksheet is made up of:

Columns — A, B, C, D...
Rows — 1, 2, 3, 4...
Cells — where rows and columns meet

For example:

means Column B, Row 4.

A group of cells is called a range.

For example:

A1:D10

Our Example Dataset

We'll use a simple sales dataset:

Date Customer Region Salesperson Product Qty Unit Price Sales
01-Aug Alpha Traders Maputo Dinis Nation PVA 10 750 7,500
02-Aug Benny Hardware Beira Laura Weather Guard 5 1,200 6,000
03-Aug City Build Maputo Dinis Primer 8 900 7,200
04-Aug Delta Supplies Nampula Imran Nation PVA 20 750 15,000
05-Aug Eastside Stores Xai-Xai Ricardo Gloss Enamel 6 1,500 9,000

Each row represents a sale.

Each column describes something about that sale.

This is the basic structure you'll see in many real-world datasets.

Basic Formatting

Formatting controls how your data looks.

You can change:

Font
Font size
Bold
Background
Borders
Alignment
Number formats
Date formats

For example:

7500

can be displayed as:

7,500.00

The formatting makes the number easier to read.

Alignment

You can align information:

Left
Center
Right
Top
Middle
Bottom

You can also use Wrap Text when text is too long for a cell.

Number and Date Formatting

Different types of information should be displayed appropriately.

Numbers
7500

can become:

7,500.00
Dates
01/08/2026

can be displayed as:

01-Aug-2026

Good formatting makes a spreadsheet easier to understand without changing the underlying data.

Sorting and Filtering Sorting

You can arrange Sales from:

Largest → Smallest

For our example:

15,000
9,000
7,500
7,200
6,000
Filtering

You can filter the dataset to show only:

Region = Maputo

Now you see only the Maputo sales.

Sorting and filtering are simple but important tools for exploring data.

Conditional Formatting

Conditional formatting automatically changes the appearance of cells when a condition is met.

For example:

Highlight all sales above 10,000.

Excel can automatically highlight:

15,000

while leaving the other values unchanged.

You can use conditional formatting to identify:

High or low sales
Duplicates
Negative values
Values above/below a target
Trends and patterns

Text Functions

Excel can also manipulate text.

CONCAT

CONCAT joins text together.

For example:

=CONCAT(B2," - ",D2)

could produce:

Alpha Traders - Dinis

This is useful when you want to combine information from multiple columns.

REPLACE

REPLACE changes part of a text string based on its position.

For example:

=REPLACE(B2,1,5,"New")

This replaces characters within the text.

Important: REPLACE works based on character position.

Core Excel Formulas

Now we can start asking questions about our sales data.

SUM

Adds values together.

=SUM(H2:H6)

Question:

What are our total sales?

AVERAGE

Calculates the average.

=AVERAGE(H2:H6)

Question:

What is the average sale?

COUNT

Counts cells containing numbers.

=COUNT(H2:H6)

Question:

How many numeric sales records do we have?

COUNTA

Counts cells that aren't empty.

=COUNTA(B2:B6)

Question:

How many customer entries do we have?

MIN and MAX

Find the smallest and largest values.

=MIN(H2:H6)
=MAX(H2:H6)

Questions:

What was the smallest sale?

What was the largest sale?

IF allows Excel to make a decision.

For example:

=IF(H2>=10000,"High","Normal")

Excel checks the sales value.

If it is 10,000 or more, it returns:

High

Otherwise:

Normal

This is the beginning of using Excel for logical analysis.

AND / OR

These allow you to test multiple conditions.

AND
=AND(C2="Maputo",H2>=10000)

This asks:

Is the sale from Maputo AND is it at least 10,000?

Both conditions must be true.

OR
=OR(C2="Maputo",C2="Beira")

This asks:

Is the sale from Maputo OR Beira?

Only one condition needs to be true.

SUMIF and SUMIFS

These allow you to calculate totals based on conditions.

SUMIF

For example:

What are the total sales in Maputo?

=SUMIF(C2:C6,"Maputo",H2:H6)
SUMIFS

SUMIFS allows multiple conditions.

For example:

What are the total Nation PVA sales in Maputo?

=SUMIFS(H2:H6,C2:C6,"Maputo",E2:E6,"Nation PVA")

COUNTIF and COUNTIFS

These count records based on conditions.

COUNTIF

How many sales came from Maputo?

=COUNTIF(C2:C6,"Maputo")
COUNTIFS

How many Nation PVA sales came from Maputo?

=COUNTIFS(C2:C6,"Maputo",E2:E6,"Nation PVA")

AVERAGEIF

AVERAGEIF calculates an average based on a condition.

For example:

What is the average sale in Maputo?

=AVERAGEIF(C2:C6,"Maputo",H2:H6)

Instead of calculating the average of every sale, Excel only uses the sales that meet the condition.

GIT AND GIT BASH

Isaac Mageto — Thu, 27 Aug 2026 08:44:38 +0000

GIT AND GIT BASH

See my first week at LUXDEV ACADEMY has been nothing short of extraordinary.

From the orientation bit – to the installation of key softwares and explanations of their workings has been just incredible.

Now am into week 2 and have gotten to learn more about GIT and GIT BASH.

Now for me I will try to break it down into a way that applies logics for simplification and understanding – so lets get into it.

1. GIT

Now Git is a software in our local computers that gets to do a bit of everything and channels communications to other key softwares in our case Git Bash (which we shall look into later) and how they get to “talk” and get your local machine upload and get you work to the public.

So first lets get through some commands and what they get to do in Git Bash.

A – THE NAVIGATION

pwd

This command gets you to know where you are at the current moment ie folder.

So the logic is if you run pwd you are telling Git Bash “where am standing at currently so that we can continue navigating through your work you need to know where you are.

$ pwd
/c/Users/isaac.mokua/OneDrive/desktop/Kenya-hospital-records-analysis

ls

If you run this command you are basically telling Git Bash “what are the current lists am working in/with within my folder or repo

then Git Bash will basically list for you the files and folders that are available.

$ ls
data/  README.md

mkdir

When you want to create a new structured folder in my case for my school work I will run the “mkdir “ command – to basically tell Git “ we are creating a new working folder in our local machine that we will be working with for our assignments and class work.

For example “MKDIR DATA “ we are creating a new folder named – data that we will be working on/with.

Note: mkdir is a "quiet" command; it doesn't "speak" unless there is an error!

$ mkdir data
$

cd

Change directory (CD).

Remember when we had created a new folder named data – so running the “Cd “ command we are telling Git – we need to move into the folder named data _ more like opening the doors to the folder named data in our local machine and get to interact with the folder.

$ cd data
isaac.mokua@CK-MOQICT-L002 MINGW64 ~/Project/data
$

2. Writing contents and reading contents

So since we are inside our folder named data we need to write the contents of the folder – basically readable contents.

So we run:

readme.md

This file is what we get to outline the workings of the file inside the data folder.

We will be outlining what we are doing within our data project as a whole to the public so that they get to better understand what we are doing.

Once ran, you will notice our readme file does not have any contents so we need to write contents.

To do this we run:

$ touch README.md
$

Echo “-“ – command

This basically will tell Git “i want to be able to write my contents in my readme file, but one important thing to note, is inorder to structure our readme file well into a well readable file we need to use the “#” command.

Echo “#---“ – this will basically create the header for our readme file
Echo “## -- “ – this command we shall be creating a subheader in our read me file.

$ echo "# Kenyan Hospital Records Analysis" > README.md
$

So finally once we do that and have added the contents we want the public to read as they get to interact with our works we can get to read the contents directly from terminal we use the:

Cat readme.md

This command when ran – Git will basically outline for you all the written contents within your readme.md file.

$ cat README.md
# Kenyan Hospital Records Analysis

Now another command in Git that helps you write contents within our readme.md file is the:

Nano readme.md

This command will open an editable panel withn Git that you will then write your contents thus the header subheaders and subsequent contents that will lie within our readme file.

So after you are done – to save use the “CTRL+O+ Enter “ to save our file, then after we are done inorder to go back to terminal use the “CTRL+X” to go back to our Git terminal.

$ nano README.md
(The screen clears and opens a text editor inside your terminal)

3. Moving our works to Git Bash

Then after we are done with this process its time for us to move our works to Git Bash – our main hub where all files and works we have done that we want the public to access in our repositories sit.

In our case we want to move contents within our data folder to GitHub.

SSH Keys

SSH – (secure shell keys) basically is a key used to connect your local PC to Git Bash – so to always avoid typing or keying in your password every now and then from terminal when working – Git offers a simple solution of a secure shell key that then becomes the safe personalised key between Git and Git Bash, so everytime you are working on anything in Git, it becomes easier to push it to your repository since Git and Git Bash have a “common key “ that is safer faster and more secure and that is able to make the 2 programs communicate and exchange “ information “ easily avoiding tiresome forms of work to a user.

$ ssh-keygen -t ed25519 -C "********@*****.com"
Generating public/private ed25519 key pair.
Enter file in which to save the key (/c/Users/isaac.mokua/.ssh/id_ed25519): 
Your identification has been saved in /c/Users/isaac.mokua/.ssh/id_ed25519
Your public key has been saved in /c/Users/isaac.mokua/.ssh/id_ed25519.pub

4. Git tracking our works

First we need Git to take charge of the works inside our Git terminal ( the ones we have had the readme file and data file” – the logic here is Git is able to track and take charge of our files, incase of anything we are able to edit or do any other checks etc to our file, as well as Git will get to know the distinctive features and works inside our data.

Remember all works are unique so Git will be able to even “know about each and offers flexibility, so we can work an other stuff as well without loosing track or works we were doing. Running this command Git automatically add the “.git” that will basically record any changes that user makes going forward.

$ git init
Initialized empty Git repository in /c/Users/isaac.mokua/Project/.git/

Git status

This command is to basically run the status or basically “where are we currently “ within our folder and the works we are conducting.

$ git status
On branch main
Untracked files:
  (use "git add <file>..." to include in what will be committed)
    README.md
    data/

Git add .

This command basically is like pushing our data folder in line – to be “ready “ to go public within Git Bash but most important thing yet to know it has not been moved its just static ready to “launch “.

$ git add .
$

5. Connecting to the repository

git remote add origin (paste your ssh git bash key)

Remember the logic of Git offering flexibility when working and making changes to your folder/data or works, this command in Git offers that – so basically the logic is you are telling Git “always make changes to this repository that am pointing you to “ since all changes and works are unique and to avoid any mixup when needing to changes on particulars of your pushed code/works to Git Bash – so Git knows what specifically to check and target/make changes to.

$ git remote add origin git@github.com:MOKUA122/Kenya-hospital-records-analysis.git
$

6. Launching our works

The Commit (Taking the Snapshot)

$ git commit -m "Initial commit: Added data and README"
[main (root-commit) 7a2b3c4] Initial commit: Added data and README
 2 files changed, 15 insertions(+)
 create mode 100644 README.md
 create mode 100644 data/Kenyan_Hospital_Health_Records.xlsx

The Push (The Launch)

$ git push -u origin main
Enumerating objects: 5, done.
Counting objects: 100% (5/5), done.
Writing objects: 100% (5/5), 450 bytes | 450.00 KiB/s, done.
Total 5 (delta 0), reused 0, pack-reused 0
To github.com:MOKUA122/Kenya-hospital-records-analysis.git
 * [new branch]      main -> main
branch 'main' set up to track 'origin/main'.