Use APKPure App
Get RPN old version APK for Android
مفيد RPN حاسبة. المصدر المفتوح. كتب في Kotlin.
Very handy calculator, in Reverse Polish Notation style. Written in Kotlin.
For every day use. Large digits with only the most used operators.
App is open-source. You'll find it at http://github/scoutant. Written with language Kotlin as alternative to Java.