When the train is crowded, please hold on tightly to the strap.

He rang the large hanging bell of the old temple.

How much is the change?

Japanese red seaperch is a delicious fish, especially used for nigiri sushi.

Please use the emergency stairs in case of a fire.

Due to the earthquake, the city declared a state of emergency.

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.