That is my personal issue.

My name is Tanaka.

I am studying Japanese.

We are going on a trip together.

Our country conducts large-scale military exercises every year.

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

He is majoring in applied mathematics at university.

He is passionate about researching pure mathematics.

He is a world-famous mathematician.

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