Suppose in history is the fraction (x^2+4x-8) / (2x).

How can i select only the enumerator in the history and copy him in the entry line?

Since partial copying to the clipboard requires you to move the cursor, it can only be done while editing, not directly from the history stack (at least in the current firmware). Therefore, copy the entire fraction to the edit line, then place the cursor at the beginning of the numerator, press Shift View (Copy) and tap Begin, then place the cursor at the end of the numerator and tap End, then tap Copy.

Although it does not answer your question per se, an easier way to get the numerator of the most recent result is numer(Ans).

Thank you, that helps. Further questions:

1. Is there a menu entry or a key for "numer"?

2. Is there also a command for the denominator?

3. Are there further commands for selecting?

1. Is there a menu entry or a key for "numer"?

CAS/Algebra/Extract/Numerator or numer()

2. Is there also a command for the denominator?

CAS/Algebra/Extract/Denominator or denom()

request HP-Prime TEAM: part command like TICAS

Example

That would be brilliant and elegant.

is required to separate a symbolic expression in all its parts, Super useful in programming