Sentence:  These figures are rendered as usual in Arabic letters and, as is well known, these are especially apt to confound the figures for 10 and 50 by a wrong (or lacking) puctuation...and those for 3 and 8 (8 being written as ح and 3 by the same letter but with an incomplete <WSD>downstrike</WSD> م). 
Meaning of the word marked with <WSD> tags:  A line that is drawn with a downward stroke.