A common question about the number of communication channels on a project is something like this:
You have 8 members on a project. One more member is added to the team. How many additional communication channels are added to the project?
Normally, people will solve this question by calculating the difference in the number of communication channels "before" and "after" adding the new member, using the formula [N*(N-1)]/2. The calculations will go like this:
Communication Channels "before" = [8*(8-1)]/2 = 28
Communication Channels "after" = [9*(9-1)]/2 = 36
Increase in communication channels = 36 - 28 = 8
Now, here's a quick way to solve this problem. Additional communication channels when a new member is added to the team is equal to the number of existing members on the team. In this case, we have 8 members on the team. So, when you add a new member, additional channels will be 8. Easy, isn't it?
Now you may ask, what if the question says that two new members are added. It's almost as simple as the previous case. Imagine that you are adding the members one at a time and use the same trick as above.
If project has 8 members, and you add one more, additional communication channels are 8. The number of team members become 9. Now if you add additional team member, the communication channels increase by 9. Therefore, if the team grows from 8 to 10 members, the number of channels increase by 8 + 9 = 17.
As you can see, using this simple trick, you can save valuable time on the PMP exam.