The science of studying the spatial form and quantitative relationship of the real world. Including arithmetic, algebra, geometry, trigonometry, calculus and so on.

2. Negative number?

A number less than zero.

3. Countdown [shǔ? Luo]

Accusation enumerates mistakes and also refers to general censure.

4. Earl [Yushi Pei]

Count or calculate.

5. Number code [sh ǔ m: n]

Cite allusions.