15 November 2008

Indian and "Arabic" numbers

I just returned from a trip to Iran and Afghanistan, where the people read and write Persian. (In Iran it is called Farsi, the Afghans call it Dari. The two relate to each other like Australian English and US-American English; they are both Persian but have their own characteristics.)
Persian uses the same numerals as Arabic:
However, I discovered that the way numbers are written in Persian and Arabic gives a strong clue to their origin: While Persian, like Arabic, is written from right to left, numbers are written from left to right, even if they occur in a line of text. In other words, they break the flow of reading: The reader arrives at the number from the right, then has to take the number in against the flow of the text, and then revert to right-to-left reading.
It seems clear to me that the reason for this rather strange convention has to be seen in the Indian origin of the Arabian numbers. The Brahmi script, the first script used for Sanskrit, was written from left to right. The Indian number system was first developed in the Brahmi script. When the Muslim scientists learned about the Indian position value number system they introduced it into Arabic in exactly the form as they had found it: They used the Indian numerals and the Indian notation.
While the Persian script remained a mystery for me during the two weeks of my travels, I became quite adept at reading and "translating" Dari numbers, because they follow our way of writing, and in a decimal position value number system you only have to remember ten numerals.