A mixed bag of Alt codes
Math symbols straddle the two Alt-code systems. The ones that made it into Windows-1252 get clean Alt+0nnn codes: Alt+0177 for ±, Alt+0215 for ×, Alt+0176 for °. The rest — ≤ ≥ √ ∞ ≈ π — only have legacy CP437 codes with no leading zero (Alt+251 for √), and a few have no Alt code at all: ≠ and − (the true minus sign) simply aren't in either table. For those, the HTML entity or a copy-paste is the honest answer.
× is not x, and − is not -
The multiplication sign × (Alt+0215) is a different character from the letter x, and the minus sign − is a different character from the hyphen on your keyboard. The typographic versions sit on the math axis of the font — they align with + and = where the keyboard stand-ins don't. In a spreadsheet nobody cares; in anything typeset, the difference is visible.
Mac users have it easy here
The Option layer covers most of this table: Option+= is ≠, Option+, and Option+. are ≤ and ≥, Option+v is √, Option+5 is ∞, Option+p is π. It's almost like someone at Apple did math homework once.
Fractions
½, ¼, and ¾ are Windows-1252 residents with real Alt codes
(Alt+0189, Alt+0188,
Alt+0190). ⅓ and ⅔ arrived later in Unicode: no Alt code,
but the entities ⅓ and ⅔ work in HTML.
Symbol data last reviewed: July 9, 2026.