skycoco8850
春芽
共回答了22个问题采纳率:95.5% 举报
简便运算
a+b+c=a+[c+b]
a*b*c=a*[c*b]
1.1272-998=1272-1000+2=272+2=274
2.2000-1348-323+1663
=2000-(1348+323)+1663
=2000-1671+1663
=2000-8
=1992
3.1996+699-502
=2000-4+700-1-502
=2700-5-502
=2700-507
=2193
4.489-(342-111)
=489-342+111
=489+111-342
=600-342
=258
1年前
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