Recently, I found that some people working with Syriac had little idea of how numerals are written in the language, so I wrote a little PDF manual to describe what is only briefly touched upon in the standard grammars.
The manual covers the various forms of numerals used in Syriac: the alphabetic numerals and the various systems of marking higher alphabetic numerals, Eastern Arabic numerals and Aramaic sign–value numerals.
The PDF can be downloaded from http://www.garzo.co.uk/documents/syriac-numerals.pdf.