1992*19911991-1991*19901990

原式=1992*1991*10001-1991*1990*10001=2*1991*10001=。。。

1992*19911991-1991*19901990
=(1991+1)*19911991-1991*19901990
=1991*19911991+19911991-1991*19901990
=1991*(19911991-19901990)+19911991
=1991*10001+19911991
=1991*(10000+1)+19911991
=19910000+1991+19911991
=39823982

1992*19911991-1991*19901990
=（1991+1）*19911991-1991*19901990
=1991*19911991+19911991-1991*19901990
=1991*(19911991-19901990)+19911991
=1991*10001+19911991
=19911991+19911991
=39823982

39823982

1992*19911991-1991*19901990
=1992（19910000+1991）-1991（19900000+1990）
=19920000*1991+1992*1991-1991*19900000-1991*1990
=20000*1991+2*1991
=39823982

1992*19911991-1991*19901990
=1992*1991*10001-1991*1990*10001
=(1992*1991-1991*1990)*10001
=1991*(1992-1990)*10001
=1991*2*10001
=3982*10001
=39823982