Thread: why are octal and hexadecimal numbers written the way they are?

Was it for convenience sake or to simply differentiate each number system from each other?

I would think, both. Programming language are generally flexible with given values, and a quick and easy way to distinguish base would be a boon.

For instance, the number "11" might mean several things depending on the base.

11₂ = 3
11₈ = 9
11₁₀ = 11
11₁₆ = 17

Sometimes, you want to use values as decimal, since this is the most common way we experience numbers in our lives (which is probably why this is the "default" interpretation of numbers).

Sometimes, you want to use binary or hexadecimal since this is the neatest way to deal with an array of bits.

Octal has its own niche where it is more convenient to use.

Is there a historical reason for it?

I'm no expert on these things, and perhaps someone else here can give you better answers to this question, but you can find some quick background on wikipedia:

Originally Posted by wikipedia

Several different notations are used to represent hexadecimal constants in computing languages; the prefix "0x" is widespread due to its use in Unix and C (and related operating systems and languages)

Hexadecimal - Wikipedia, the free encyclopedia

Originally Posted by wikipedia

In programming languages, octal literals are typically identified with a variety of prefixes, including the digit 0, the letters o or q, or the digit–letter combination 0o. In Motorola convention, octal numbers are prefixed with @, whereas a small letter o is added as a postfix following the Intel convention. DR-DOS DEBUG uses \ to prefix octal numbers.

Octal - Wikipedia, the free encyclopedia