第 7 条 · 算术与代数

Arithmetic treats of numbers in particular, and is the science of numbers properly so called; but this science extends only to certain methods of calculation which occur in common practice.

算术处理具体的数，严格说来就是数的科学；但它只延伸到日常实践中常见的某些计算方法。

Algebra, on the contrary, comprehends in general all the cases that can exist in the doctrine and calculation of numbers.

代数则相反，它一般地包含数的理论和计算中可能出现的一切情形。