Good afternoon, Pak Ryder There's a rule for it. However, it's quite complicated even for Indonesian speaker. This is how I comprehend it. There are affixes which change a verb into a noun. They are : 1) the prefix pe-(N.) 2) the combination of prefix and suffix: pe-(N)+-an Here are some examples: - bantu (to help) --> membantu --> pembantu (the housemaid/helper) - beli (to buy)--> membeli --> pembeli (the buyer) pembelian (purchasing) - beri (to give) --> memberi --> pemberi (the giver) pemberian (gift) - 1 buat (to make) --> membuat --> pembuat (the maker) pembuatan (the making of) 2 buat (to do) --> berbuat --> perbuatan (conduct) - jual (to sell) --> menjual --> penjual (the seller) penjualan (sale) - kerja (to work) --> bekerja --> pekerja (the worker) pekerjaan (work/job/task) - urus (to take care) --> mengurus --> pengurus (the caretaker) pengurusan (the management) My conclusions are: 1) When you know how to change the verb in root word into an active voice form, then you will be able to change it into a noun. Because the letters follow prefix pe-(N.) depends on the inflections. 2) The prefix pe-(N.) is used to change a verb into a doer (like the suffix -er in English). 3) The combination of prefix and suffix pe-(N.) + -an is used to change a verb into a noun which describes the process or the method of something. So, the first thing you have to do is to grasp the active voice of verbs. The keyword is usually the first letter of the verb. Hope they help, Terecia