用简便方法计算下面各题
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| ①125×7×8 =(125×8)×7 =1000×7 =7000; ②25×(4×98) =(25×4)×98 =100×98 =9800; ③(675+321)+325 =(675+325)+321 =1000+321 =1321; ④(31×5)×(2×7) =(31×7)×(5×2) =217×10 =2170; ⑤125×4×8×25 =(125×8)×(4×25) =1000×100 =100000; ⑥229+137+171+363 =(229+171)+(137+363) =400+500 =900. |
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a.12×(4+25)[ ]
a. 47+(14×5)(1)35+65=
65+35=
35+65○65+35