01   #include <math.h>
02   #include <stdio.h>
03  
04   int main()
05   {
06     double x = 4.0, result;
07  
08     result = sqrt(x);
09     printf("The square root of %lf is %lfn", x, result);
10     return 0;
11  } 

 OUTPUT :
 
 The square root of 4.000000 is 2.000000