The American youth's instructor; or, A new and easy guide to practical arithmetic : Wherein the rudiments of common arithmetic, vulgar the decimal fractions [as printed], the extraction and use of the square and cube roots, &c. are so easily treated of, and so plainly demonstrated, that any person may, of himself (in a short time) become acquainted with every thing neccessary to the knowledge of business. : To which is added a postscript for the use of country youths in particular; shewing how to measure any regular pas printed /