Lesson 6 of 7
Binary Basics
Master the language of 1s and 0s and learn how computers represent numbers, letters, and pixels with switches.
Learn it
Inside a computer are billions of microscopic electronic switches called transistors. A switch can only ever be in one of two states: ON or OFF.
Because switches only have two states, computers use the Binary number system (base-2), which uses only two digits: 1 (ON) and 0 (OFF).
A single 1 or 0 is called a BIT. When you group 8 bits together, you get a BYTE! Using bytes, computers can represent numbers, text letters, colours, and music.
Key terms
- Bit
- The smallest unit of data in computing; a binary digit that holds either a 0 or a 1.
- Byte
- A group of 8 bits capable of representing 256 unique values (0 to 255).
- Transistor
- A microscopic semiconductor switch that controls the flow of electrical current to represent binary states.
- ASCII
- American Standard Code for Information Interchange; a character-encoding standard that maps numbers to text characters.
Converting Binary to Denary (Decimal)
Learn how to convert the 8-bit binary byte 00101010 into a standard base-10 number.
- 11. Write Place Values: Place values for an 8-bit byte are: 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1.
- 22. Align the Bits: Write the binary bits underneath: 0 | 0 | 1 | 0 | 1 | 0 | 1 | 0.
- 33. Add Active Values: Sum the place values that have a 1: 32 + 8 + 2 = 42.
- 44. Verify the Result: Binary 00101010 equals decimal 42! In ASCII, 42 represents the asterisk character (*).
Converting Text to Binary in Python
python# Convert each character of a string into its 8-bit binary representation
word = 'CODE'
for char in word:
ascii_code = ord(char) # Get numeric ASCII decimal
binary_repr = f'{ascii_code:08b}' # Format as 8-bit binary string
print(f'Char: {char} | ASCII: {ascii_code:3d} | Binary: {binary_repr}')This script uses Python's ord() function and string formatting to show the direct link between human letters, ASCII codes, and 8-bit binary strings.
Try it
Complete the Python code to convert the binary string '00001101' (decimal 13) into an integer by specifying base 2.
binary_string = '00001101'
decimal_value = int(binary_string, ______)
print('Decimal result:', decimal_value)Challenge
Calculate the binary representation of the decimal number 155 using an 8-bit byte.
Pick whichever way suits you — every mode earns the same bonus XP.
Write at least 40 more characters to submit.
Mark your own work
Guided walkthrough — 0/5 clues revealed
- Clue 1 locked — reveal it only if you get stuck.
- Clue 2 locked — reveal it only if you get stuck.
- Clue 3 locked — reveal it only if you get stuck.
- Clue 4 locked — reveal it only if you get stuck.
- Clue 5 locked — reveal it only if you get stuck.
Each clue costs 4 XP (never below 20 XP). You'd earn 40 XP right now.
Extension: Explain how hexadecimal (base-16) is used as a shorthand for binary and why one hex digit represents exactly 4 bits (a nibble).