0.9+0.99+0.999+0.999-3=?怎样算最简便呢?

原式=0.999+1-0.1+1-0.01+1-0.001-3
=0.999+3-3-0.1-0.01-0.001
=0.999-0.1-0.01-0.001
=0.888
关键在于利用重复了两次了0.999,因为之前化简得出了减去0.1,0.01,0.001即是0.999的十分位、百分位、千分位的数值各减去1,较为简便

原式=1-0.1+1-0.01+2(1-0.001)
=4-0.112
=3.888

（1-0.1)+(1-0.01)+(1-0.001)-3
=3-3-0.111
=-0.111

=(1-0.1)+(1-0.01)+(1-0.001)+(1-0.001)-3
=4-3-0.112
=1-0.112
=0.888