While the decimal numbering system allows any digit in a number to have any of ten values (0-9), digits in hexadecimal numbers can have 16 (0-F), digits in octal numbers only eight (0-7) and ...

The octal number 10 represents the number 8 in decimal. The octal 100 represents 8 × 8, or 64. 1000 is 8 × 8 × 8, or 512. One dollar in base ten would convert over to $1.44 in base eight, and ...

It's simple: I specified that I wanted octal (base-8) output, but by using the leading zero, I also indicated that I was specifying a value in octal too. Ergo, 0500 = 500. That's nice, but no binary, ...