Lesson 1

Numbering system

Binary numbers

Origin of binary numbers. That meant zeros and ones. 10101010....

As of today, computers run on electricity. It only knows on and off. Computers have millions of tidy little switches. 1 for on, 0 for off.

So to express numbers like 4 it needs to be written like 00000100

Examples of binary numbers

Decimal | Binary
1       = 00000001
2       = 00000010
3       = 00000011
4       = 00000100
5       = 00000101
6       = 00000110

Octal

Octagon, prefix oct means 8. That means octal numbers start from 0 to 7. Counting 0 and all together it's 8 numbers.

Decimal | Octal
0       = 0
1       = 1
2       = 2
3       = 3
4       = 4
5       = 5
6       = 6
7       = 7
----------> here is how octal representation differs
8       = 10
9       = 11
10      = 12

Hexidecimal

FF A0 ....... boring boring boring but hecidecimal and binary numbers are like the most boring and yet exciting couple you will ever meet. We will come back to this later. I promise!

REPL - whaa...?

When you open a terminal and type python you are getting into REPL mode.

> python
1 + 1
2

REPL mode allows you to test out simple python code. It can come in handy.

I encourage to have fun by writing code to break your computer. Learning to code is all about making silly mistakes. If you make enough silly mistakes then you end up with awesome code.

Hello World

print("hello world")

Variables

Just like we say that person's name is mo and his age is 25. Computers can do something similar.

name = "mo"
age  = 25

name and age are called variables in computer programming.

name is a variable that stores string data type, meaning it stores text. age is a variable that stores int data type, meaning it store numbers.

Run the following code

print(f"{name} is {age} years old")

It will output something like

mo is 25 years old