Translation:One trillion won
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In fact, all the names of currencies in East Asia (Chinese yuan, Japanese yen, Korean won, Mongolian tugrik / tögrög) stem from the word 'circle'. One explanation to this fact is that we once (in pre-modern eras) used silver dollars that were round like a circle.
The Japanese yen and Korean won directly use the (ancient) Chinese reading of the character 圆 'circle' (圓 in the traditional script), and the Mongolian tögrög is a native word which means 'a circle'.
There were still circles in the xiaozhuan script, and all cursive strokes had to become more straight lines / rectangles in Han dynasty's lishu (~ the 2nd century B.C.). The transformation was due to the change of writing tools (straight strokes were more efficient).