The first of five clues. Each one below gives a little more away.
For most of human history I did not exist, and arithmetic managed without me.
Rome built an empire without me, and could not have written the year 2000.
India gave me a name and a set of rules, and the idea travelled west through Baghdad.
Divide by me and mathematics refuses to answer.
The digit that means nothing and changes everything.
Zero
Brahmagupta set out the rules for it in 628 AD, including — correctly — that division by it has no answer. Europe resisted the whole idea for another five hundred years.
Babylonians used a placeholder mark, but a placeholder is not a number. The step that mattered was treating nothing as a quantity you can add, subtract and reason about, and that appears in Brahmagupta's Brahmasphutasiddhanta in 628 AD, complete with the rules — including that division by it yields no answer. The idea travelled through Baghdad into al-Khwarizmi's arithmetic and reached Europe with Fibonacci in 1202, where several Italian cities banned the new numerals as a fraud risk, since an unscrupulous clerk could turn a nought into a six far more easily than he could alter XVIII.
Reading five clues at once is not the game. In the real thing they arrive one at a time and every wrong guess costs an hour. Play mystery #37 · today's mystery · the vault
Previous: mystery #36. Next: mystery #38. Or try #45, #46, #47, #48, #49, #50.