Pycharm does not identify the Math module

When writing import math Pycharm underlines math with a red line and, when hovering a cursor, gives out No module named math . Math itself works, i.e. When executing the code

   import  math  print  (math.pi)   

I get the cherished 3.14...

However, Pycharm does not recognize this module and it does not have it in the External Libraries. How to make Pycharm "see" it again?