Arithmetic (noun)

1. The branch of mathematics concerned with addition, subtraction, multiplication, and division.
2. The process or an instance of calculation.

Origin:

Late middle english: via old french from latin arithmetica, from greek arithmētikē (tekhnē) "(art) of numbers", from arithmos "number".

Examples:

1. She was skilled in arithmetic, able to solve complex problems quickly and accurately.
2. The arithmetic of budgets and finances can be a difficult and confusing subject.
3. The arithmetic of voting systems can sometimes lead to unexpected results.
4. The arithmetic of population growth and resources can have serious implications for the future.
5. The arithmetic of the stock market can be both fascinating and mystifying.