Why Do We Count in Tens?
When man even in his uncivilized state found it necessary to count, the only implements at hand were his fingers and toes, and as he had ten toes and ten fingers, he naturally began counting in tens, and has been doing so ever since.
When we to-day count on our fingers we confine ourselves to our fingers leaving our toes stay in our shoes, where they naturally belong. But the first men who counted used both fingers and toes, and so he was able to count twenty before he had to begin over again, while little children to-day, when they count with their fingers, must begin where they started after they reach ten.