IMPLICIT REAL*8(A-H,O-Z)
      integer*4 i, n
      n  = 1000000000
      pi = 0.0
      s  = 1.0
      do i=1,n
         x = i
         pi = pi + 6.0/x**2
      end do
      pi = sqrt(pi)
      WRITE(6,*) 'n=',n,'  pi=',pi
      STOP
      END