How much is $100 US?

Could you please clarify what you mean by "How much is $100 US?" Are you asking for the value of $100 in a different currency? Or perhaps you're wondering about the purchasing power of $100 in the United States? If it's the latter, the answer would depend on a variety of factors such as the current inflation rate, the cost of living in different regions, and the specific goods or services you're interested in purchasing. If you could provide more context, I'd be happy to give you a more specific answer.