Thank you all! So there are so many "and" for every comma and after hundred! Thank you!

For example, 52,305,982,520 USD is --> United States Dollars Fifty Two Billion and Three Hundred Five Million and Nine Hundred Eighty Two Thousand and Five Hundred Twenty? Is this right or wrong? Please correct me. If I were only mimicking the written number, I'd say: "Fifty two billion, three hundred and five million, nine hundred and eighty two thousand, five hundred and twenty United States dollars." In writing or conversation, I'd say something like, "The amount in US currency is fifty two billion, three hundred and five million, nine hundred and eighty two thousand, five hundred and twenty dollars."

The "and" is after "hundred", and confusingly after "thousand" if the number following it is less than 100. So 365 is "three hundred and sixty five", 1,065 is "one thousand and sixty five" and 1,365 is "one thousand three hundred and sixty five". In your example it should be "Fifty Two Billion and Three Hundred and Five Million and Nine Hundred and Eighty Two Thousand, Five Hundred and Twenty?"

There is no good reason to write long numbers in words instead of numbers, and in fact it makes it much harder for the brain to register. The only time it is recommended to write numbers in words is for single digits (1-9) and if a number (regardless of the number of digits) begins a sentence. So don't write 75 people attended, rather Seventy-five people attended.

You can put "and" after 982 thousand. But it isn't necessary