AI says:
This appears to be a German inscription from inside an old book, likely from 1906. It reads: Dieses Buch No. ___________ wurde am Ostern 1906 in Lindenwalde gekauft und hat f. 75 Mk. gekostet. Translated to English: "This book No. ___________ was bought at Easter 1906 in Lindenwalde and cost f. 75 Marks. The "f." before "75 Mk." likely indicates a fractional amount (perhaps 75 pfennigs or a portion of a Mark). ```
Looks more like a 1 than an f though,