Calculating World Currency

I decided to count up the number of currencies I've used since my trip began. The total is 13! They are:

1. US Dollar
2. European Union Euro (France, Spain, Austria, Italy)
3. Jordan Dinar
4. Syrian Pound (called lira)
5. Lebanese Pound
6. Uganda Shilling
7. Rwanda Franc
8. Ethiopia Birr
9. British Pound
10. United Arab Emirates Duram
11. China RMB (called quai)
12. Vietnam Dong
13. Hong Kong Dollar

You may wonder how I've dealt with so many currencies. My method is simple. If the exchange rate is MORE than one per US dollar (Shilling, Quai, Dong, etc.), I convert in my head to US dollars. If the exchange rate is LESS than one per US dollar (Pound, Euro), I pretend it is a US dollar. It's not until I get my credit card bill or look at my bank account that my conversion method seems erroneous. By then, it is too late, and my method continues on. . .