Letternumber

Letternumber is a general term used to describe systems that assign numerical values to letters of the alphabet, or to use letters to encode numbers. In its simplest form, letters are mapped to ordinal values such as A=1 through Z=26, an approach often called A1Z26. Other schemes use A=0 or a reversed scheme where Z=1.

Common uses include cryptography, puzzle design, and educational exercises. The A1Z26 cipher is a classical example: HELLO becomes 8-5-12-12-15. When concatenated without separators, HELLO reads as 85121215, which can create ambiguity, so separators or parsing rules are often used. Beyond ciphers, letternumber systems appear in numerology and gematria-like traditions, as well as data encoding and word games where letter values influence scores or indexing.

Variants extend the concept by combining letter values with other schemes, using modulo operations to fit numbers into a fixed range, or including case-insensitive mapping, padding, or checksums.

Computationally, letternumber conversions can be implemented with simple tables or arithmetic formulas, allowing rapid translation between text and numbers, and enabling features such as similarity scoring, ranking, or encoding of identifiers.

Related topics include alphanumeric ciphers, gematria and isopsephy, A1Z26 and other alphabet-number mappings, and general encoding schemes for natural language processing and cryptography.