1.(9999²+1999)/500000
=(100000000-20000+1)/500000
=99980001/500000
=199.96002
2.1998*20002000-2000*19981998
=1998*20000000+1998*2000-2000*19980000-2000*1998
=0
1.(9999²+1999)/500000
=(100000000-20000+1)/500000
=99980001/500000
=199.96002
2.1998*20002000-2000*19981998
=1998*20000000+1998*2000-2000*19980000-2000*1998
=0