解:如图
999*999+1999
=999*(1000-1)+1999
=999*1000-999+1999
=999000-(1000-1)+(2000-1)
=999000+1000
=1000000
999×999+1999
=1000×999-1×999+2000-1
=999000-999+2000-1
=999000+2000-1000
=999000+1000
=1000000
999*999+1999
=999*999+999+1000
=999*1000+1000
=1000*1000
=1000000