Combinatorics is a branch of mathematics dealing with issues of order and choice.

I love mathematics.

He is passionate about researching pure mathematics.

He is majoring in applied mathematics at university.

He is a world-famous mathematician.

Combinatorics is a branch of mathematics that studies combinations of things.

Combinatorics is a branch of mathematics that studies combinations of things.

Discrete mathematics is an important field that forms the basis of computer science.

He made a selection from the menu.

He is working in the field of science.