From Riches to DONGGGGGG

Seven Hundred thousand dong is what your date will cost you at a lobster dinner.
One hundred thousand dong will buy you a good local meal.
20 thousand dong is what you'd tip a bellboy in a 5 star hotel (you tip virtually no-where else).
3000 dong is your parking fee for your motorcycle at the lot.
500 dong can be burned for fuel.

It gets confusing. You deal with a lot of zeros.
What else is confusing is your 10,000s look almost identical to your 100,000s and your 50,000s can be confused with your 500,000s. And all bills are fronted with a smiling Ho Chi Minh. When paying a bill, pay it slowly.

And here's something you didn't know. Banks and hotels give crummy exchange rates. But private shops are even worse. There is one place we exchange money--at a local jewelry store.
$100 can be exchanged for 1.9 million dong (who wants to be a millionaire? In dong? Anybody?). There is no way anyone but a shrewd local could know this, and without my Vietnamese escort they'd probably add on a "foreigner tax."

Here's something else you don't know. For us, 100 dollar bills equals $100, as do 5 20s. But somehow Vietnamese prefer $100 notes. So you will get bad exchanges for anything lower. They will even take off points if it's not a crisp note or has a bad fold in it. What the hell? Are they trading notes like baseball cards? Whatever the reason, be advised.