[ZeroGravitas]

"For fractions, we say three fifths. The Chinese is literally, 'out of five parts, take three.'"

You could also say that three-fifths is literally "out of five parts take three" too, just more tersely. I'll give them the benefit of the doubt that in Chinese languages the meaning has not atrophied to the same degree or is more verbosely specified (which kind of counters the brevity argument they use for integer digits).

[jhancock]

Perhaps a bilingual Chinese person could weigh in on this. For this exercise, we are concerned with the language in their head, not what they say when they talk to another. I'm guessing they think in terms of math notation with word-numbers, so "3/5" in their head would be "one-syllable-number" "slash" "one-syllable-number".