How to convert powers of 2 number to multiples of 10 number?

Question

I would like to create a function which converts powers of 2 to multiples of 10. can anybody help in providing algorithm such that function should use only integers .. Should not use ang float variable.

FUN_Convert(100,524247,1024) /*100->10^2,524247->511.96*1024, 1024 -> 2^10*/
    {
      int a;
      /*Do calculation*/ 

      return a; /*calculated value 51195*/
    }