It's easy to find out how many combinations you can have if you know the total number of items, and the number of items you are combining.
It's a little harder to do that in reverse. This document shows how to find the total number of items if you know how many are combined at a time, and the total number of combinations.
The use of technological resources in education has lead to positive changes in the elaboration of new methodologies, in this context technologies such as the Digital Interactive Whiteboard (DIW) can act by facilitating Learning. The mere presence of the DIW does not guarantee benefits for the student's learning process, that raises doubts about whether or not the resources available are used in a satisfactory manner. In this research it was possible to verify that there are few tools available for the DIW context, and many of them have problems of usability and content quality. Thus, a form of facilitate the content elaboration for the DIW is the use of Authoring Tools (ATs). In order to verify whether or not the use of ATs promotes better use of the DIW, an AT (entitled AtauDIW) was developed to assist the use of DIWs.
A System Design Language provides a means of communicating a design and an approach to determine the effectiveness of a design before it is built. This design language helps to guide the decomposition of the design by asking the right questions at the right time. The process of deﬁning system requirements, communicating these requirements and their chosen solutions, and determining the effectiveness is explained within this primer.