Captain Smith sends an away team to check out a completely new, uncharted planet, and they discover the ruins of an ancient pre-warp civilization. Artifacts and pictures suggest the creators of the civilization were four legged beings, that had one long tentacle coming out of their back, with the tentacle branching at the end with a number of grasping "fingers". Many of the artifacts contain inscriptions that appear to be mathematical, and the first to be translated (with limited away-team gear) comes out as the equation
5x^2 - 50x + 125 = 0
with the indicated solutions x = 5 and x = 8. The first solution looked right, but the second was puzzling. Seven-of-Nine (as she often does) quickly came up with an explanation: like that of humans, the base of the number system for this civilization is equal to the total number of fingers. So how many fingers did these beings have? Please explain.
Explain the civilization to the number.