# Binary

This article is about the numeral system. For the extraction element sometimes involving converting eight-bit binary numbers into characters, see ASCII. For the binary-based extraction element that is encoded using two different writing styles, see Bacon Cipher.

Binary is a Numeral System and a communications-based Decryption element, most famous for its role in computer science. Binary is one of the most commonly-used ciphers in puzzlehunting, along with Morse Code, Braille, and Flag Semaphore.

## Background

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### Finger Binary

Finger Binary is a variation on regular, five-bit binary, involving the assignment of binary digits to hand digits.

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## Puzzle Applications

Binary can be used in two ways: in its ordinary capacity as a Numeral System and (as a corollary of the Alphanumeric Substitution Cipher) as an Extraction element.

### Binary as a numeral system

Main article: Numeral System

Binary, formally Base-2, can operate just like any other base in puzzlehunts. This generally involves converting between base-2 and a different base, often base-10.

### Binary as an extraction

What distinguishes Binary as a puzzling element is its role as an extraction element. Its most common form is five-bit binary, where an extraction from five items of binary nature can be interpreted to obtain a number from 1 to 26, and from there a letter by way of the Alphanumeric Substitution Cipher (A1Z26).

 1 0 0 1 1 (19) 0 0 0 0 1 (1) 0 1 1 0 1 (13) 1 0 0 0 0 (16) 0 1 1 0 0 (12) 0 0 1 0 1 (5)

This step generally comes unclued, since its usage comes from being a corollary of the A1Z26 cipher. In general, the translation to binary has a clear indicator of what is 1 and what is 0, or use typical connotations of 1 vs 0 in binary: high vs low, true vs false, on vs off, present vs absent. Also occasionally used is the graphical similarity of 1 and 0 to the letters I and O.

Binary extractions generally come in two forms: one form groups objects of binary nature into ordered quintets, while the other has a set of five ordered binary conditions that an object can either satisfy or not (e.g. whether a word contains each of the five English vowels). Either way, the arrangement of the bits, both within a single letter and within the puzzle as a whole, should be unambiguous.

## Strategy

This section discusses binary exclusively as an extraction element. For general strategies regarding numeral systems, see Numeral Systems.

### Spotting the usage of Binary

The usage of Binary, unlike most other Decryption Elements, is mostly left unclued. In the few puzzles where it is clued, the title and flavortext can either use the word "bit" directly or otherwise refer indirectly to how to extract binary from the puzzle. Keep an eye out for the words "one" and "zero" in flavortext, as they may tell you what other elements of the puzzle are assigned to each digit.

Regardless of whether the flavortext hints at it or not, if the puzzle consistently groups its objects into fives, it's very likely that a binary extraction will be involved. Likewise, see if the objects in the puzzle have a defining quality that lends itself easily to an ordered set of five, or if the flavortext clues towards such a set; these are also tells for a binary extraction.

### Translating Binary

Base converters are prevalent online, and one can choose to translate binary into decimal using one of these tools. If using Excel or Google Sheets to solve, one may find it convenient to use the BIN2DEC formula. To save time on transcription, however, one may wish to memorize the binary encodings for the English letters. While easy to derive with mental math and knowledge of A1Z26, it may be worthwhile to associate specific patterns of bits with their corresponding letters instead, often the vowels (00001, 00101, 01001, 01111, and 10101 in that order) and some common consonants.

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