

I had to dig quite a bit into the paper to find it:
English and up to 21 other languages (Bengali, Catalan, Danish, German, Esperanto, Spanish, Finnish, French, Hindi, Hungarian, Indonesian, Italian, Japanese, Dutch, Norwegian, Polish, Portuguese, Russian, Swedish, Thai, Chinese)
Frankly that’s poor sampling — 18/22 of the languages are Indo-European and/or spoken mostly in Europe.















The article explains it, but the origin is from Latin ⟨ad⟩ for, toward, at in the Middle Ages. Faster to write, less paper and ink necessary (those can be expensive).
There’s a bunch other symbols and diacritics that popped up back then, for roughly the same reasons. From what I recall:
*old spellings. Modern ⟨dieci⟩ and ⟨piño⟩ / ⟨pinho⟩ respectively.