This lecture is devoted to multi scale numerical models available for solving various problems in research on materials processing and in industrial applications. The first part of the lecture is devoted to macro, micro, mezo and nano scale modeling techniques. The basis of the commonly used methods are presented. Their advantages as well as disadvantages are discussed. The second part of the lecture is focused on the multi scale modeling techniques. Problems of classification (concurrent, upscaling, coupled, uncoupled), scale bridging (space, time) and computational efficiency will be discussed. Examples of applications and possibilities provided by these multi scale method in industrial applications will be presented as well.