用简便方法计算.
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| (1)125×(8×4) =125×8×4 =1000×4 =4000 (2)125×(8+4) =125×8+125×4 =1000+500 =1500 (3)71×101 =71×(100+1) =71×100+71×1 =7100+71 =7171 (4)71×101-71 =71×(101-1) =71×100 =7100 (5)25×28 =25×4×7 =100×7 =700 (6)25×29 =25×(30-1) =25×30-25×1 =750-25 =725 (7)43×7+47×7 =(43+47)×7 =90×7 =630 (8)54+137+26+63 =(54+26)+(137+63) =80+200 =280 (9)567+297 =567+(300-3) =567+300-3 =867-3 =864 (10)127×19-27×19 =(127-27)×19 =100×19 =1900 |
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a.12×(4+25)[ ]
a. 47+(14×5)(1)35+65=
65+35=
35+65○65+35