1.1111×1.9999-0.1111×0.9999
=1.1111×（1+0.9999）-0.1111×0.9999
=1.1111×1+1.1111×0.9999-0.1111×0.9999
=1.1111+（1.1111-0.1111）×0.9999
=1.1111+1×0.9999
=1.1111+0.9999
=2.111
愿对你有所帮助!