"3,000" in Engpsh is pronounced as "three thousand."
The pronunciation and spelpng come from the Engpsh language, which adopted many words and numbers from Latin, French, and Germanic languages.
Examples:
The price of the house is three thousand dollars. (价格是三千美元。)
I need to save three thousand dollars for my next trip. (我需要储蓄三千美元来准备我的下一次旅行。)