Willsfords arithmetick, naturall, and artificiall: or, decimalls. Containing the science of numbers, digested in three books. Made compendious and facile for all ingenious capacities, viz: merchants, citizens, sea-men, accomptants, &c. Together with the theorie and practice united in a sympathetical proportion betwixt lines and numbers, in their quantitites and qualities, as in respect of form, figure, magnitude and affection: demonstrated by geometrie, illustrated by calculations, and confirmed with variety of examples in every species. / By Thomas Willsford, Gent.

To extract a Cubique root from any mixt or compoun∣ded fraction, when either Numerator, or Denomi∣nator, or both are incommensurable, or the improper fraction a perfect Cube. Example 10.

The mixt or com∣pound 〈 math 〉〈 math 〉 Cube here pro∣pounded is 4492 ⅛, which if reduced into an improper Fraction will bee 35937/8 a Cu∣bique number whose Root is required, in∣scribe the Denomina∣tor as 35937 at A, and having pointed it, find the Root of 35, which will be 3, set it in the Quoti∣ent, and take the Cube of it 27 out of 35 the re∣mainder will be 8; this done triple the Root 3 and finde the Index, as 9 & 27 against B, & C, under these draw a line, and finde a new Root as 3 again, whose Cube is 27 against D, the Square of it multi∣plied by the Triple is 81 as at E. Thirdly, the Root and Index multiplied together, viz: 3 & 27 produ∣ceth also 81 as F, the totall G 8937, subtracted

from the remaining Cube 8937 nothing will re∣main in the Numerator of this fraction, whose De∣nominator was 8, and the Cubique root of it is 2, so the true Root of 4492 ⅛, or which is all one, this improper fraction 35937/8 will be 33/2 or 16 ½; and if supposed feet, it is the length of a statute Pole, whose Cube made upon this Root or side is 4492 ⅛ as before.