THE RECORD
What changed
Indian mathematicians developed decimal place value and treated zero as placeholder and number; Brahmagupta described rules for it in 628.
EVIDENCE
What remains
The Bakhshali manuscript, Gwalior inscription and Brahmagupta's Brahmasphutasiddhanta preserve stages of development.
WHY IT MATTERS
Why it matters
It made complex calculation portable and supported commerce, astronomy and algebra.
OPEN QUESTION
Where interpretation begins
Zero was not invented in one instant, and other cultures used placeholders; numeral forms changed during transmission.