MOLCAS manual: 3.1 Introduction Start running MOLCAS 7.4 just requires a small number of operations. This section of the manual, "How to run MOLCAS in a nutshell", is addressed to those who want to immediately run some simple calculation to become familiar with the program. Here we include the basic hints to begin with: setting the proper environment, building some simple inputs, running the calculation, and extracting the information obtained.