Q. I am planning to spend three days in Hong Kong as part of a longer trip. Can I use US dollars or must I get Hong Kong dollars?
A. The US dollar remains the leading global currency. In many locations - such as parts of Latin America or Africa - you could get on just fine with American dollars. But the Hong Kong dollar is up there with the Swiss franc and the Norwegian krone as a strong and independent currency - and just as it would be unusual and problematic to try to use US dollars in Zurich or Oslo, so too you would have difficulties spending US$ in Hong Kong.
Happily, changing sterling for Hong Kong dollars is very straightforward, with reasonable rates at the airport and healthy competition among moneychangers at street level. The rate you should aim for is HK$12 for each pound.
You should find that Hong Kong is excellent value. Any spare HK$ should be changed before you leave the former colony, because you will get better rates there than in Britain.