Marlin31 Dec 15, 2019:

"4/5 of the plate length - Sure, it's OK. Just google it or "1/3 of the plate length" (more common phrase)

Frank Szmulowicz, Ph. D. Dec 15, 2019:

Let's say the plate is 100 centimeters long. After the front of the mobile phase has moved across 80 centimeters of the plate (that is 4/5 of its length), the plate is removed from the chamber.

Alexander Grabowski (asker) Dec 15, 2019:

Thank you Frank But "4/5" parts of the plate length"
"4/5 of the plate length"
Do these examples really make sense?