Why do blind people hold hands when telling fortune?

What is the use of "pinching fingers" in "counting fingers"? Why are a few fingers pinching around for show or can they really play any role?

It's definitely not a show

Fortune-telling needs the cooperation of cadres and branches, but the calculation of cadres and branches is very troublesome. To imagine the mutual cooperation between 12 and 10, paper and pencil are generally needed, but the ancients rarely had the opportunity to use paper and pencil when calculating numerology. So divide your fingers into three sections and fix them for 12 days. When matching with the earthly branches, you need to read the earthly branches according to your knuckles, so that you can calculate the heavenly stems and earthly branches of the year and month more quickly.