1. 算术
    Arithmetic is the part of mathematics that is concerned with the addition, subtraction, multiplication, and division of numbers.

    e.g. ...teaching the basics of reading, writing and arithmetic.
           教授阅读、写作和算术的基础知识
    e.g. ...an arithmetic test.
           算术测验

2. 演算；计算
    You can use arithmetic to refer to the process of doing a particular sum or calculation.

    e.g. 4,000 women put in ten rupees each, which if my arithmetic is right adds up to 40,000 rupees.
           4,000名妇女每人放入10个卢比，如果我算得对的话，总数将达到4万卢比。

3. （某形势的）数据统计
    If you refer to the arithmetic of a situation, you are concerned with those aspects of it that can be expressed in numbers, and how they affect the situation.

    e.g. The budgetary arithmetic suggests that government borrowing is set to surge...
           预算数字表明政府借款将要大幅增加。
    e.g. The arithmetic is finely balanced: the socialists and their allies do not have an overall majority.
           该估算是经过仔细权衡的：社会主义者和他们的同盟并不占绝大多数。

4. 算术的;运算的
    Arithmetic means relating to or consisting of calculations involving numbers.

    e.g. ...a processor which performs simple arithmetic operations such as adding or multiplying numbers.
           可进行加法或乘法等简单运算的处理器