Although polydactylism affects about 0.2% of the population, the fact that #5 represent the other 99.8%’s amount of fingers per hand may be one of the most important factors in the way society organizes itself. Because most people have two hands, your value became the midpoint from 0 to 10, with 9 in the highest place for a single digit. This is known as the base 10 system, which was developed in many ancient societies. Some societies even made you the base- a base 5 system! This made 4 the largest single digit possible. In that way, 5 was never written down as it is now, but as 10. Gladly, we ditched that difficult system. Modern math uses the base 10 system.
Imagine if 5 didn’t exist at all? If people stopped on the fourth finger and had no opposable thumb? Not only would humans probably fail to develop half (50%, haha!) of the tools they did, as building would be difficult without grasping abilities, but we’d have a base 4 system! Things would be organized so strangely. Counting would go: 1, 2, 3, 10, 11, 12, 13, 20, 21, 22, 23, 30, 31, 32, and suddenly 100! I can’t imagine percentages, an economic system, or metric system where 100 came so fast! What would the coins look like? Or standard measurements?
5's existence is as important as the opposable thumb. Things would be complicated without it. I hope #5 enjoy's it's value!