How Base-N Systems Work
A base-N number system represents values using N distinct digits, starting from 0 and ending at N-1.
Binary (base-2) uses just 0 and 1, octal (base-8) uses 0-7, decimal (base-10) uses 0-9, and hexadecimal (base-16) extends digits with letters A through F to represent values 10 through 15.
Each digit's position carries a weight equal to the base raised to the power of its position, counting from right to left starting at zero.
So the binary number 101 equals 1×4 + 0×2 + 1×1, which is 5 in decimal.
Knowing the base tells you exactly how to interpret each digit's place value during conversion.