This is the 130th most frequent Indonesian word.
per
"Per" in Indonesian can mean "per" (as in "per unit") or "spring" (mechanical coil).
per is used to indicate a rate or distribution per unit (each copy in this case)
Harga buku ini adalah 50.000 rupiah per eksemplar.
The price of this book is 50,000 rupiah per copy.
per denotes the frequency of an activity within a specific time period (per week)
Kami berlatih bulu tangkis dua kali per minggu.
We practice badminton twice per week.
per is used to denote the starting point of implementation (as of)