Unicode plus a few special symbols can encode most mathematical expressions in readable plain text. The format is linear, but can be displayed in built-up form. The approach uses heuristics to recognize mathematical expressions without the aid of explicit math-on/off commands. This is facilitated by Unicode's new strong support for mathematical symbols. This plain-text approach is compared to standard TeX, Unicode TeX, and MathML. The plain-text representation is dramatically more compact and easy to read. Keyboard input methods are discussed. One use of the plain-text format is as a math input method, both for search text and for general editing. Export to TeX, MathML, C++, and symbolic manipulation programs is outlined.