Mathematical economics

Mathematical economics is the sub-field of economics that explores the
mathematical aspects of economic systems. Modern mainstream economic
research typically makes extensive use of mathematical modelling. As a
result, the distinction between mathematical and non-mathematical economics
is less clear today than it once was.

Mathematical economics can be regarded as the "theoretical" counterpart of
Econometrics, which attempts to analyse the real world of economic activity
using statistical techniques.

The mathematical tools economists use are often applied in other sciences as well.