Fun with Japanese Numbers

"You've been in Japan too long when you're speaking English with your gaijin friends, but all references to money are in Japanese." This is a funny phenomenon, but true: even when speaking English, foreigners living in Japan will tend to use Japanese for numbers and yen money amounts. The reason is that the Sino-Japanese numeric system, which came from China, is clunky when converting to the Arabic numeric system. The number system revolves around the unit 10,000 (man, pronounced mahn), rather than 1,000; thus, the number 10,000 is 1 man (ichi mahn、一万), 20,000 yen is 2 man (ni mahn、二万), 100,000 is 10 man (juu mahn、十万) and so on. The conversion from one numeric system to the other is just frustrating enough that most foreigners will be happy to leave their numbers in Japanese, if the person they're talking with understands the words. If you think it's difficult learning to think in units of 10,000, you should try doing math with the kanji-based numbers that come after man, which are oku (億、equal to 100 million), cho (兆、1 trillion) and kei (10 quadrillion, which is so high that I never bothered to learn the kanji for it).