Is it necessary for preschool children to learn hand-brain quick calculation?

Second, hand-brain quick calculation (finger calculation) and primary school mathematics

1: hand index, using hands instead of abacus, like abacus mental arithmetic, the concept that the number calculated by hand tools has no number runs counter to the teaching method of primary school mathematics. Primary school math teachers are particularly opposed to this method.

2. Students' hands are constantly moving when calculating the problem, and then do it after finishing the problem. It's a waste of time and your fingers are not up to standard. (The first grade of primary school requires oral calculation for 5 minutes. 100 Question)

The primary school math teacher said: It is very difficult for students to get rid of the bad habit of calculating problems with their fingers. Finger is the worst study habit in mathematics. It relies on fingers instead of brains to calculate problems. The end result is that children's thinking ability is delayed and their brains are dull.