History of the threepence the possible advent of a decimal currency at the time (see florin), when the 3d at 1/80th of a pound would not have fitted within a decimal system). Currency silver threepences from 1838 to 1926 were of identical design and cannot usually be distinguished except in the best conditions when the higher striking standard of the maundy coins stand out; this resulted in the curious legal anomaly that when the currency was decimalised in 1971 "all" silver threepences from 1870 onwards were revalued at three new pence, not just the maundy coins. Threepences were produced with both the "young head"
Decimal decimal fractions were non-positional. However, counting rod fractions were positional. Qin Jiushao in his book Mathematical Treatise in Nine Sections (1247) denoted 0.96644 by J. Lennart Berggren notes that positional decimal fractions appear for the first time in a book by the Arab mathematician Abu'l-Hasan al-Uqlidisi written in the 10th century. The Jewish mathematician Immanuel Bonfils used decimal fractions around 1350, anticipating Simon Stevin, but did not develop any notation to represent them. The Persian mathematician Jamshīd al-Kāshī claimed to have discovered decimal fractions himself in the 15th century. Al Khwarizmi introduced fraction to Islamic countries in the early 9th