Applied mathematics refers to mathematics that can be directly applied to practice. In the long run and in a broad sense, mathematics should be useful. Even number theory, which purely studies the inherent regularity of integers, has now found its use in cryptography and other fields. So the boundary between applied mathematics and basic mathematics is not so clear.

Extended data

Vertically, mathematics can be divided into four stages: elementary mathematics and ancient mathematics, variable mathematics, modern mathematics and modern mathematics.

From a horizontal perspective, that is, from the internal structure of mathematics, different countries have different classification methods. At present, mathematics in China is divided into five branches, namely, basic mathematics, applied mathematics, computational mathematics, probability statistics, operational research and cybernetics.

It should be noted that the above classification method is based on decades of practice in China, and different countries have different views on this issue.