The twenty-first edition of the ready reckoner; or, Trader's sure guide : Containing tables ready cast up, adapted to the use of all who deal by wholesale or retail; exhibiting, at one view, the amount or value of any number of quantity of goods or merchandize, from one up to ten thousand, at the various prices, from one farthing to one pound. To which are prefixed, I. A table, directing how to buy and sell by the hundred; and, II. Tables of the amount of expences, &c. by the day, week, month, and year. And at the end are added, I. Tables of interest, at five per cent. per annum, from one pound to five hundred pounds, and from one to three hundred and sixty-five days. II. Tables of commission, or brokerage, from one eighth to one pound per cent. on any sum, from one shilling to ten thousand pounds. III. A table, shewing the number of days, from any day in one month to the same day in any other. By William Leybourne.