Readers come to Arbital pages with different levels of mathematical background. This page gives guidelines for writing pages for some of the most common audiences, with more details on the individual pages.
Math 0
Math 0 readers have little to no knowledge of mathematical notation or concepts outside of basic arithmetic. Use wordy explanations rather than concise notation, and cushion any use of letter variables with images or careful descriptions. In general, try to write pages with as few requisites as you can for this level.
Okay to expect: Informal ideas of Number, [-addition], [-subtraction], [-multiplication], maybe [-division].
Avoid where possible: [Algebra], any formula that could look remotely scary, moving too fast.
Math 1
Math 1 readers are "good at math" in a colloquial sense. They have some knowledge of algebra and [-geometry], which they can use to solve problems and basic puzzles. A U.S. junior high graduate may be a math 1 reader.
If you think it would help intuitions form faster, don't stop using images just because you can explain a concept through notation at this level.
Okay: Basic use of variables, very basic and entirely hand-held formulas, [-exponentiation], square root, [-bodmas]
Avoid: Non-trivial formulas (unless they're a centerpiece and you have paragraphs deconstructing it), advanced notation,
Math 2
Math 2 readers have a strong understanding of at least one branch of mathematics, often due to having a professional role involving mathematically structured thought (e.g. programmer, engineer) or advanced education. They have a well-integrated model of basic mathematical concepts, experience with at least some moderately advanced ideas, and a framework for integrating new concepts.
Math 3
Readers at the Math 3 level have knowledge of research-level mathematics, and have worked with formal mathematical concepts and proofs. They are familiar with axiomatic derivations of sets and abstract structures.
Proficiency at the Math 3 level corresponds roughly to the math education level of a university student with an undergraduate degree in mathematics or higher.