Our decimal number system – which is based on the numbers one through ten – was inspired by the ten fingers (and toes) of your ancestors. That’s why the world digit means ‘’finger’’ in many languages. If we had evolved with, say, seven numbers (once we counted to seven, we’d move right to eleven). And it would seem totally natural to us.
The human hand has 5 fingers, or to be precise, one thumb and four fingers. So, with both hands, it’s very easy to count to 10. In this case, there’s no particular order in which an individual assigns a value to a particular finger. The little finger on his left hand could very well be 5 or 6, according to each person’s preference. The only requirement is that the individual never repeats the use of the same finger.
Most people probably use the three segments (knuckle spaces) on their fingers to count even higher. Each segment would count as one number, bringing the highest possible count to 12 when using 4 fingers on each hand. In this method, there is also no preference for any particular finger, although the individual is required to follow a single direction, namely up-down or down-up, to avoid errors.
Picture Credit : Google