The first Friday prayer is held at Al-Azhar

Aryabhata's notation encoded numbers through syllables, showing that mathematical representation can take forms other than modern written numerals.

The new Abbasid capital was founded on 30 July 762 and became a major center for scholarship, administration and translation.

Naubakht and Masha'allah reportedly selected an astrologically auspicious moment, illustrating the close relationship between mathematical astronomy and state planning.

The city's multilingual scholarly environment later supported translations and original work in arithmetic, algebra, geometry and astronomy.

Baghdad's planned circular form joined surveying, geometry, architecture and imperial symbolism in a major urban project.

Alongside religious and linguistic studies, scholars taught inheritance arithmetic, astronomy, timekeeping and related mathematical subjects.

Al-Azhar shows how mathematics was transmitted through teaching communities rather than only through famous books and individuals.

Students from Africa, Asia and the wider Islamic world carried methods and texts across linguistic and political boundaries.

The Abbasid caliph surrendered on 10 February 1258, followed by the sack of a city central to centuries of scientific exchange.

Libraries and institutions suffered catastrophic loss, although the familiar story that all books were thrown into the Tigris cannot be treated as a precise inventory.