Can I use RMB for shopping in Da Nang?

Most local shops don't accept RMB. Of course, there are still many shops in China that can accept RMB, but the exchange rate conversion is poor. If you can see that the receptionist is fluent in Chinese, try asking. It's convenient to bring dollars, and the local tip is generally around 2 dollars. Moreover, many local UnionPay ATMs in Da Nang can insert UnionPay cards to directly withdraw Vietnamese dong, which is very convenient.