In English, the number 400 is written as "four hundred." The number comes from the Hindu-Arabic numeral system, where it is represented by the symbol "400."

For example:

The house is 400 meters away from the grocery store. (这所房子距离杂货店400米。)

The temperature will be around 400 degrees Celsius today. (今天温度大约将会达到400摄氏度。)

The company has a net worth of over $400 million. (该公司净资产超过4亿美元。)