mathematics - How did the obelus ÷ come to stand for division . . . The formula with the obelus is merely tabulated by Rahn with no text, and if the motivation was known, Cajori would have mentioned it in History Of Mathematical Notations, which is a classical treatise It is likely that Rahn (or Pell) simply repurposed the minus sign symbol, it was used from Riese's algebra textbook (1525) onward
How did Hindu-Arabic Numerals get their shapes? I’ve noticed a recurring post on social media that presents an image suggesting the shapes of Hindu-Arabic numerals are connected to the angles within their design: This claim seems dubious to me
mathematics - How long has the order of priority of arithmetical . . . This question comes up often, but there is no up to date scholarly study of it that I know of The most comprehensive recent accounts (and they are rather brief) seem to be Jeff Miller's Earliest Uses of Symbols of Operation and Peterson's post on Math Forum, parts of which are aped on various pop-sites, often without attribution
Why is the radical symbol $\\sqrt{}$ called radical? "Radical" comes from Latin "radicalis", having roots, an equivalent "radix" was also commonly used earlier While Rudolff did use the radix in 1525 his did not have the overbar on top, now called vinculum, Latin for
How did Hertzsprung-Russell diagrams end up so confusing? HR diagrams show in which of several sequences individual stars fall, each respecting the rough principle that hotter stars are of higher luminosity (Sequences other than the main sequence may ben
How did the theory of the Horus-eye fractions originate? In a book, I saw a short anecdote about something called the "Horus-eye" hieroglyph, supposedly used in parts to represent fractions (the book dates to 1997) Wikipedia has an article on the symbol