Octal uses 8 digits (0-7) and is primarily used in some traditional computer systems and Unix file permissions.

• Uses digits 0-7
• Widely used in early computer systems
• Each octal digit represents 3 binary bits
• Often uses '0' prefix, such as '0o755'

Decimal is our everyday number system, using digits 0-9.

• Uses digits 0-9
• Most commonly used numbering system by humans
• Each position has a weight of powers of 10
• Example: 123 = 1×10² + 2×10¹ + 3×10⁰