Numerical digit
From India, the thriving trade between Islamic sultans and Africa carried the concept to Cairo. Arabic mathematicians extended the system to include decimal fractions, and Muḥammad ibn Mūsā al-Ḵwārizmī wrote an important work about it in the 9th  century. The modern Arabic numerals were introduced to Europe with the translation of this work in the 12th century in Spain and Leonardo of Pisa's "Liber Abaci" of 1201. In Europe, the complete Indian system with the zero was derived from the Arabs in the 12th century.
Tunisian Arabic
The first successful trial to create a specific Latin script and writing method for Tunisian was the "Practical Orthography of Tunisian Arabic", created by Joseph Jourdan in 1913. Its principle was to use French consonant and vowel digraphs and phonology to transcribe non-Latin sounds. In this method, "kh" is used to
transcribe /χ/, "ch" to transcribe /ʃ/, "th" to transcribe /θ/, "gh" to transcribe /ʁ/, "dh" to transcribe /ð/ or /ðˤ/ and "ou" to transcribe /u:/, "a" to transcribe /a:/ and /ɛː/, i to transcribe /i:/ and e to transcribe the short vowels. The layout was successful because it did not involve additional Latin letters and could be transcribed efficiently. It was used in the later linguistic works of Joseph Jourdan about Tunisian Arabic until 1956. Moreover, it is still presently used in French books to transcribe Tunisian Arabic. The method was used in 1995 by the Tunisian Arabizi, an Arabic chat alphabet, converting the consonant digraphs into digits. It uses 2 to transcribe a glottal stop, 3 to transcribe /ʕ/, 5 to transcribe /χ/, 6 to transcribe /tˤ/, 7 to transcribe /ħ/, 8 to transcribe /ʁ/ and 9 to transcribe /q/. The ch, dh, and th digraphs were kept in Tunisian Arabizi. Vowels are transcribed according to their quality and not to their length as a is used to transcribe short and long [ɐ] and [æ], e is used to transcribe short and long [ɛ] and [e], u is used to transcribe short and long [y], eu is used to transcribe short and long [œ], o is used to transcribe short and long [o], ou is used to transcribe short and long [u] and i is used to transcribe short and long [i] and [ɪ]. Sometimes, users differentiate between short and long vowels by dropping short ones. Like all other Arabic chat alphabets, its use spread considerably during the 1990s mainly with the Tunisian young people. Nowadays, it is used principally on social networks and mobile phones. Also, during the Tunisian Revolution of 2011, Tunisian Arabizi was the main script used for message transmission on internet. After 2011, more interest was given to Tunisian Arabizi and in 2013, a concise grammar book about Tunisian, written with Tunisian Arabizi, was issued. In 2016, Tunisian Arabizi has been recognized by "Ethnologue" as an official informal script for writing Tunisian. However, this chat alphabet is not standardized and is seen as informal as the Arabic sounds are transcribed as numbers and letters at the same time. The use of digits as numerals and letters at the same time made transcribing Tunisian difficult to users and did not linguistically solve the matters that were faced by the Practical Transcription.