My husband has started learning Japanese. We have been playing shopkeeper using real money every day. I now understand why his coin collection has been growing so quickly. Japanese coins are small. If you have been using them since childhood, you probably won't mistake a 1 yen coin for a 100 yen coin at a glance. However, foreigners with less sharp eyesight have to read the numbers engraved on them every time, which can be time-consuming. I also recently noticed that even though 5 yen coins have "五円" engraved on them, they do not have the number 5.
Don't read them, feel them! Or better yet, memorize them! That's the key.
Part of the reason my husband struggles with the coins may be due to living in a cashless society and not being accustomed to using physical currency. I'm still hesitant to let him handle the coins on his own outside.
