用简便方法计算.
6.3+6.44+2.7+3.56??????????????
15.35-(5.35+7.2)
600÷12
67×101?????????????????
125×16×45?????????????????
8×(125×25)
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解:(1)6.3+6.44+2.7+3.56,
=(6.3+2.7)+(6.44+3.56),
=9+10,
=19;
??????????????????????
15.35-(5.35+7.2),
=15.35-5.35-7.2,
=10-7.2,
=2.8;
600÷12,
=600÷6÷2,
=100÷2,
=50;
67×101,
=67×(100+1),
=67×100+67,
=6700+67,
=6767;
?????????????????
125×16×45,
=125×(8×2)×45,
=(125×8)×(2×45),
=1000×90,
=90000;
?????????????????
8×(125×25),
=8×125×25,
=1000×25,
=25000.
解析分析:(1)利用加法交换率和结合律把6.3和2.7,6.44和3.56结合;
(2)利用连减的简算方法计算即可;
(3)将600÷12变形为600÷6÷2,再简算方法计算即可;
(4)将67×101变形为67×(100+1),再利用乘法分配律计算;
(5)将125×16×45变形为125×8×2×45,再利用乘法分结合律计算;
(6)利用乘法分结合律计算.
点评:此题考查运用运算定律简便计算,解决此题的关键是运用加法交换率和结合律,乘法交换率、结合律以及分配律使计算简便.