wàn​fēn HSK7

extremely

万分 (萬分) wàn​fēn
extremely adverb
very much; to a high degree

I express my utmost gratitude for your generous help.

ten-thousandth numeral
one ten-thousandth part

The error requirements for this technology must be controlled at the ten-thousandth level.

Frequency

Movie subtitles
7.30 per million appears in 4% of films
Written text
10.6 per million

Details

HSK 2.0
Level 6
HSK 3.0
Level 7

Sources

Definitions
CC-CEDICT