what do we got dental formula of adult human 2123/2123????

I think you want to ask how do we get dental formula of adult human 2123/2123. 

All 32 teeth are of 4 different types- Incisors, Canines, Premolars and Molars.

I- Incisors

C- Canines

PM- Premolars

M- Molars

The formula 2123 for upper teeth indicates 2 incisors, 1 canine, 2 premolars, and 3 molars on one side of the upper mouth and lower mouth. It means there are total 16 teeth on one side of mouth. When we consider other side of mouth, it also has 16 teeth. So, in total, there are 32 teeth in humans.