Find how many communication channels exist in a team and how many new channels each additional person adds.
Channels = n × (n − 1) ÷ 2 where n is the number of stakeholders including the project manager. Channels grow much faster than headcount: 5 people → 10 channels, 10 people → 45, 20 people → 190.
Questions often add or remove people and ask for the increase – calculate both values and subtract. Always check whether the PM is already counted in the number given.
Yes, count everyone who communicates, including the project manager. Read the question carefully – if it says 'team of 6 plus the PM' use 7.
10 × 9 ÷ 2 = 45 channels.
It shows how quickly communication complexity grows with team size, which is why a communications management plan is needed.