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the formula is simple but the application trips people up

Communication Planning

n(n-1)/2

Channels Formula

Counts potential communication channels

3

Methods

Interactive, Push, Pull

45

10-Person Channels

Add one person and you gain 10 channels

one more person explodes the complexity

n(n − 1)/2 Curve

Channels grow quadratically. That is why small teams communicate easily and large teams drown.

0501001502003p · 3ch5p · 10ch10p · 45ch15p · 105ch20p · 190ch+1 person = +10 channelsnumber of peoplechannels

channels = n × (n − 1) / 2

Three Methods · Direction of Flow

Interactive

two-way, real-time

Meetings, calls, video. Best for sensitive, complex, or urgent topics.

Push

one-way, broadcast

Email, reports, memos. Best for routine updates.

Pull

recipient-initiated

Wikis, dashboards, repositories. Best for reference content.

Exam Traps

The formula counts potential, not required channels

n(n-1)/2 shows how complexity grows, not how many conversations you must have. Answers that interpret it as required comms are wrong.

Push is not interactive

Email and reports are push — one-way delivery. If the exam asks for the best method for sensitive or complex information, the answer is interactive (face-to-face or meeting).

Information radiators are public

Kanban boards, burndown charts, and team dashboards are information radiators. They display status, not confidential information. Answers that treat them as private are wrong.

Complex or sensitive = interactive

Any question about conveying emotion, negotiating, or resolving misunderstanding leads to face-to-face or video, never email.

Complexity explodes fast

10 people = 45 channels. 11 people = 55 channels. That is 10 more channels from ONE person.

Match method to content

Urgent or emotional → interactive. Reference → pull. Broadcast → push.

1
Two People, One Channel

You and one friend have one conversation going. Simple.

2
Three People, Three Channels

You + A, you + B, A + B. Add a person and the conversations multiply.

3
Ten People, Forty-Five Channels

n(n-1)/2 = 10 × 9 / 2 = 45. That is why big group chats become chaos.

4
One More Person Makes It Worse

Going from 10 to 11 adds 10 more channels. That is why adding stakeholders is not free.

n times n minus one, divided by two. Add one person, feel the pain.
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Reviewed by Chris K., PrepSolution Content Editor, Project Management
Sources verified against PMI 2026 standards
Updated May 2026