Use the style of your discipline when writing numerals. If your discipline does not clearly define a style then use the APA Manual or Turabian as a guide for when to write a number as a word or as a numeral. Never begin a sentence with a number written as a numeral. Spell it out or reword the sentence so that a number does not begin a sentence. This applies to chemical compounds and other terms which commonly begin with a numeral.
Punctuation Be consistent with comma usage.
However, students following APA and MLA must use the comma. The dash is overused so consider using another punctuation mark. Using et al.'s is not acceptable. Statistical Symbols Statistical symbols must be italicized or underlined in text, tables, figures, and appendices. The APA Manual discusses this extensively and contains numerous examples.