He was surprised to hear the news.

He was surprised when his friend played a practical joke on him.

To welcome the New Year, we decorated the entrance of our house with Kadomatsu.

The thirty-first day is my birthday.

He defeated the enemy using the Thirty-Six Stratagems.

In China, a strict birth control policy was implemented at one time.

He is good at arithmetic operations.

Arithmetic operators are symbols used for mathematical calculations.

Please calculate the arithmetic mean of this dataset.

Please do not walk in this room with your outdoor shoes on.