I’m watching a show (Ascendance of a Bookworm) and the characters remark that it’s surprising that someone can do math without an abacus. It is a fantasy show, but it got me wondering.
Who and when invented the modern methods of addition, subtraction, and multiplication of large numbers? I’m talking about the method where you stack the numbers vertically, and think of the numbers like columns, calculating each semi-separately.
What you're talking about are known as Arabic or Hindu numerals, which use positional notation (so the columnar location matters and can be taken advantage of). They derive from methods developed originally in India, but migrated, diffused, and built-upon by scholars in Persia and the Arabian peninsula, especially during the Abbasid Empire (750-1250CE, the "Islamic Golden Age"). These involve using early versions of the numerals you are familiar with today, stacking them in columns, algebra, etc. None of our modern techniques were invented once in one place, but were developed over centuries, and spread to Europe during the Middle Ages, where it (very slowly) displaced both the abacus and Roman numerals.