"In 771, a traveller arrived in the city [Baghdad] with a copy of a work of Hindu astronomy called the Siddhanta (The Opening of the Universe), by the Indian mathematician . Unlike Euclid, Brahmagupta did not set out his mathematical propositions clearly with proofs, but obscured them (as was traditional in Indian mathematics) under a veil of poetry — beautiful, but extremely difficult to unravel. Al-Mansur gave his court astrologer, al-Fazari, the Herculean task of translating the Siddhanta, which introduced Baghdad to the concept of 'positional notation' – the way we write numbers to this day, using the digits 1 to 9, in columns of units, tens, hundreds and so on. The possibilities that this system opened up were limitless; when it was eventually adopted, it transformed the entire discipline of mathematics by allowing calculations that would have been impossible with the old Roman-numeral system. Positional notation was already known in Syria and had been admired by , who wrote about the 'nine sings' of Indian mathematicians in 662."