マイナス記号 vs ハイフン

The minus sign (−, U+2212) is a proper mathematical operator designed to align visually with the plus sign (+) and equal sign (=) at the same height and weight, while the hyphen-minus (-, U+002D) is an ASCII character that serves triple duty as a hyphen, minus sign, and list bullet in plain text. In professionally typeset mathematics, using the true minus sign (U+2212) is strongly preferred because it has the correct optical weight and vertical alignment for mathematical expressions. Programming languages and most calculators use the hyphen-minus for subtraction due to its presence on every keyboard and in ASCII, so developers often see and type U+002D in code contexts. Screen readers may interpret the two characters differently: some will say “minus” for U+2212 and “hyphen” or remain silent for U+002D, making the choice important for accessibility in mathematical content. When publishing math on the web, consider using MathML or a library like MathJax to handle these distinctions automatically rather than relying on raw Unicode characters.