I don't know about you, but I write my 1 in just one stroke of the pen. Also I use a space as a thousands separator, and you need to write 一万 in Japanese for 10 000, not just 万 by itself. That makes for a closer game:
一 / 1 (one stroke vs one)
十 / 10 (two strokes vs two)
一万 / 10 000 (or 10K) (four strokes vs five)
When you get to numbers like 5462, there's no contest versus 五千四百六十二.
一 / 1 (one stroke vs three)
十 / 10 (two strokes vs four)
万 / 10,000 (three strokes vs seven)