millennium later, their appellation became the English word "zero" after a tortuous journey of translations and transliterations from India to Europe. (See Zero: Etymology.) In addition to Surya Prajnapti, important Jain works on mathematics included the Sthananga Sutra (c. 300 BCE – 200 CE); the Anuyogadwara Sutra (c. 200 BCE – 100 CE), which includes the earliest known description of factorials in Indian mathematics; and the Satkhandagama (c. 2nd century CE). Important Jain mathematicians included Bhadrabahu (d. 298 BCE), the author of two astronomical works, the Bhadrabahavi-Samhita and a commentary on the Surya Prajinapti; Yativrisham Acharya (c. 176 BCE), who authored a mathematical text called Tiloyapannati; and Umasvati (c. 150 BCE), who, although better known for his influential writings on Jain philosophy and metaphysics, composed a mathematical work called Tattwarthadhigama-Sutra Bhashya. Oral tradition Mathematicians of ancient and early medieval India were almost all Sanskrit pandits ( "learned man"), who were trained in Sanskrit language and literature, and possessed "a common stock of knowledge in grammar (), exegesis () and logic (nyāya)." Memorisation of "what is heard" (śruti in Sanskrit) through recitation played a major role in the transmission of sacred texts in ancient India. Memorisation and recitation was also used to transmit philosophical and literary works, as well as treatises on ritual and grammar. Modern scholars of ancient India have noted the "truly remarkable achievements of the Indian pandits who have preserved enormously bulky texts orally for millennia." Styles of memorisation Prodigious energy was expended by ancient Indian culture in ensuring that these texts were transmitted from generation to generation with inordinate fidelity. For example, memorisation of the sacred Vedas included up to eleven forms of recitation of the same text. The texts were subsequently "proof-read" by comparing the different recited versions. Forms of recitation included the (literally "mesh recitation") in which every two adjacent words in the text were first recited in their original order, then repeated in the reverse order, and finally repeated in the original order. The recitation thus proceeded as: word1word2, word2word1, word1word2; word2word3, word3word2, word2word3; ... In another form of recitation, (literally "flag recitation") a sequence of N words were recited (and memorised) by pairing the first two and last two words and then proceeding as: word1word2, wordN − 1wordN; word2word3, wordN − 2wordN − 1; ..; wordN − 1wordN, word1word2; The most complex form of recitation, (literally "dense recitation"), according to , took the