Math notation conventions Please Read Wikipedia Manual of Style mathematics There is a difference between the following two things m n 3k 1 or 3k 1 m n 3k 1 or 3k 1 In non TeX mathematical notation like this variables but NOT digits and not punctuation are to be italicized a minus sign is not a mere hyphen and spaces preceed and follow plus or minus signs and the like Also displayed TeX is indented by an initial hyphen thus the second of the following is right Also note that the title phrase should be set in bold at its first appearance see WP MOS