Arabic (ish?) Numerals
Where our digits come from
5–30–17, Adil (published 6–26–17)
You all know that our beloved digits 0 1 2 3 4 5 6 7 8 9 are referred to as “Arabic numerals.” While traveling through Morocco and seeing these very familiar glyphs mixed into Arabic words on signage, it was striking to see the juxtaposition of 2 “languages.”
Then I asked myself: why do we use Arabic numerals but not letters?
FWIW, the full sign from above actually looks like this:
(So obviously they are using the same number system in both languages. Couldn’t find a good example online, but it’s more jarring when you see a number mid-Arabic sentence. This is especially interesting considering Arabic is read right to left; indeed, numbers are then also of course “read” right to left by Arab speakers. But for me, it was weird reading right-left and then switching to something I’ve only ever read left-right, then switching back to right-left to finish the sentence.)
It turns out the answer is a bit complicated. The first issue to tackle is the name of the numeral system itself. In fact, our 0–9 digits are only called “Arabic numerals” by those in the Americas and Europe. This is because the system was first introduced to Europeans in the 10th century AD by Arabic speakers from North Africa. Arabs themselves actually refer to these digits as “Hindu numerals,” referring to the fact that the digits were first used in the Indian subcontinent.
To make matters even more confusing, Arabs also refer to a separate system of “Hindi numerals” which look like the bottom row here:
Of course, we must then also have a different name for this number system since we can’t use “Arabic numerals.” Alas, Americans and Europeans call these digits Eastern Arabic numerals. So technically, our 0–9 are more fully named Western Arabic numerals.
Eastern Arabic digits and their variations are the predominant system in some of the Middle East, such as Iran and Afghanistan. So here’s what the full table looks like:
In the rest of Arabic-speaking Asia + Egypt, Sudan, and Saudi Arabia, both systems are actually used alongside each other. So yes, our “Arabic numerals” are not actually used exclusively in Arab countries. Interestingly, Western Arabic numerals are apparently used more extensively in Pakistan because the people are quite familiar with English (though again, both are used).
Mini FF: Alongside Urdu, English is the co-official language of Pakistan, used throughout the government, military, and educational systems. In fact, it is one of very few countries where English is a co-official majority language (dark blue on map below).
The Constitution and laws for the country were even originally crafted in English. However, the government announced plans in 2015 to remove this status for English and thus make Urdu the sole official language.
Aaaanyway, back to numbers and history. The major difference between Arabic numerals and Roman numerals, and the big advantage of the former, is the fact that the Arabic version includes a “place” system, where digits have different values depending on their place in the number (i.e. we have the tens place, hundreds place, etc.). This is much more graceful than the unwieldy Roman system. Key to this place system is the number 0, which was “invented” in the seventh century AD by the Indian mathematician Brahmagupta. This bro was the first to give rules to compute with zero. As you would guess, the invention of 0 is contentious and uncertain; ancient Babylonians also recorded 0-like symbols in the third century BC, but it wasn’t until the Indians did their thing that it went beyond a placeholder to become its own unique value with its own properties.
Noting its utility, the Indian system was adopted by Arab mathematicians (especially in Baghdad) and passed further and further west. After the fall of the Roman Empire, Islamic countries were the stronghold for intellectualism and mathematics, with Baghdad at its center. Two prominent mathematicians — the Persian Al-Khwarizmi and the Arab Al-Kindi wrote books in Arabic that were largely responsible for the diffusion of the numeral system first throughout the Middle East and eventually the West. The Middle-Easterners took the Indian system to the next level by adding decimals and fractions by the 10th century.
From the 980s, future Pope Sylvester II used his authority to start spreading knowledge about the system, which he learned about in his youth while studying in Barcelona (remember, Muslims ruled Spain for ~800 years). The digits’ current forms were likely finalized in North Africa, where ya boi Leonardo Fibonacci went to study. More specifically, he went to the city of Béjaïa in Algeria. Fibonacci then promoted the numeral system in his 1202 book Liber Abaci, which propelled the Hindu-Arabic system into prominence throughout Europe. This European acceptance was then accelerated by the printing press, and by the 15th century (surprisingly not that long ago?), the system was widely known throughout the continent.
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