Ex:8 - page 129

      sum1=0
      sum2=0

      do 20 n=1,1000
         sum1 = sum1 + ( 1/(n**2) )
 20   continue

      do 30 n=1,100
         sum2 = sum2 + ( 1/(n**2) )
 30   continue

      pi1=sqrt(6*sum1)
      pi2=sqrt(6*sum2)

      write(*,*)pi1,pi2

      stop
      end