The phrase "a protest of five" is correct and usable in written English.
It can be used to refer to a protest that involves five individuals or a group of five people participating in the protest.
Example: "The organizers reported that a protest of five gathered outside the city hall to voice their concerns."
Alternatives: "a demonstration of five" or "a rally of five".
She said that last spring she had become so fed up with the coalition government that she had organized a protest of a hundred and eight herdsmen.
A protest of several thousand took place only a few days ago on a major highway in the suburbs of the capital.
The unions also organized a protest of several hundred people outside their building, which grew when students fled the campus of the University of Jordan because they said arrests were being made.
The result was a protest of one thousand gathered outside the store.
He also reportedly told authorities that his alleged crime was a protest of his two cousins, serving life sentences in an Israeli prison, being denied family visits.
Recently, squatters occupied a derelict building on Great Eastern Street that developers want to turn into a hotel and held a "Bike Ride of Fury" — a protest on two wheels.
What had begun as a protest of a few hundred had become a large protest of a few thousand.
A total of 26 people are now facing conspiracy charges in federal court in Oregon for participating in the Malheur militia standoff, which began as a protest of the imprisonment of two local ranchers.
(A parallel source of agitation was America's recent invasion of Cambodia, which led to the killings, during a May antiwar protest, of four students at Kent State University by Ohio National Guard troops).
This is a parody of the mass protests of five years ago: the enthusiasm and spirit which drove the orange revolution is long gone and protesters on both sides can only be enticed with a bribe.
