RPN

RPN may refer to:

Science and technology

Real projective space (<math>\mathbb{R}\mathrm{P}^n,</math>), a type of topological space
Reverse Polish notation, a.k.a. postfix notation, a mathematical notation
Registered Parameter Number, in MIDI
Recherche en Prévision Numérique, weather forecasting research service, Canada
Risk priority number in failure analysis such as FMEA, taking into account the severity, probability and detection probability of a failure event