The ground of arts : teaching the perfect worke and practise of arithmeticke, both in whole numbers and fractions, after a more easie and exact forme then in former time hath beene set foorth: made by Mr. Robert Record Dr. in Physicke. Afterwards augmented by Mr. Iohn Dee. And since enlarged with a third part of rules of practise, abridged into a briefer method then hitherto hath beene published, with diuers necessary rules incident to the trade of merchandise: with tables of the valuation of all coynes as they are currant at this present time. By Iohn Mellis. Whereunto is added a compendium of interest, with a table of board and timber measure. Calculated by R.N. Gent. And now diligently perused, corrected, illustrated and inlarged; with an appendix of figurate numbers, and the extraction of their rootes: by Robert Hartwell, philomathematicus.