Lux mercatoria : Arithmetick natural and decimal; digested into a more easie and exact method for resolving the most practical and useful questions than hath been yet published. Wherein the most critical questions of reduction, trucks, and exchanges of monies, weights and measures of forein countries, from 5 numbers to 13, heretofore wrought by 3. 4. 5. or more operations in the Golden Rule, are now performed by one, and the fractional parts thereof explained by the monies, weights and measures of England, and make familiar to mean capacities. With a modest examination of divers rules formerly set forth by others, and a clear eviction of their errors and insufficiency, as well in decimal as natural arithmetick. Whereunto are added tables computed for the forbearance, discompt, and purchase of annuities, leases, and pensions at 6 and 8 l. per cent. Interest for forty years. /