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用递等式计算.(写出必要的计算过程,能简便计算...

(1)7.06×2.4-5.7,=16.944-5.7,=11.244; (2)5.4×99+5.4,=5.4×(99+1),=5.4×100,=540;(3)9.6×72+9.6×28,=9.6×(72+28),=9.6×100,=960;(4)(1.25×2.5)×4,=1.25×(2.5×4),=1.25×10,=12.5;(5)10.4+72×0.81,=10.4+58.32...

(1)7.9×12.5,=(8-0.1)×12.5,=8×12.5-1×12.5,=100-12.5,=87.5;(2)25.38-1.43-4.38-4.57,=25.38-4.38-1.43-4.57,=(25.38-4.38)-(1.43-4.57),=21-6,=15;(3)90+10÷0.4×2.5,=90+25×2.5,=90+62.5,=152.5;(4)0.8×0.4×(7....

①(9.4-5.8)×2.07,=3.6×2.07,=7.452;②12.54-4.56-3.44-1.54,=(12.54-1.54)-(4.56+3.44),=11-8,=3;③(9.36×5+9.36+9.36×2)×1.25,=9.36×(5+2+1)×1.25,=9.36×8×1.25,=9.36×(8×1.25),=93.6;④7.236÷0.18-14.3×0.02,=40.2-0.28...

(1)28×105+7236÷18=2940+402=3342(2)4.5-3.15+0.5×8=4.5-3.15+4=5.35(3)8.5×5.3+3.7×8.5+8.5=8.5×(5.3+3.7+1)=8.5×10=85(4)(0.7+1.7)×15-36=2.4×15-36=36-36=0

(1)45.07+(4.93+8.62),=45.07+13.55,=58.62;(2)12.5×(80+0.8),=12.5×80+12.5×0.8,=1000+10,=1010;(3)34.26+47.7-55.3+2.53,=34.26+(47.7+2.53)-55.3,=34.26+50.23-55.3,=84.49-55.3,=29.19;(4)13.2-180÷45×2.6,=13.2...

如图

12.5X1.6X2.5 =12.5XO.4X(4X2.5) =5x1O =5O 4O1X0.32 =400X0.32十O.32 =128+O.32 =128.32

(1)2.8×7.6+1.4×2.8+2.8=2.8×(7.6+1.4+1)=2.8×10=28;(2)70.8-0.8×0.5=70.8-0.4=70.4;(3)13-3.79-6.21=13-(3.79+6.21)=13-10=3;(4)5×(40+0.7)=5×40+5×0.7=200+3.5=203.5;(5)4.12-1.78-1.22=4.12-(1.78+1.22)=4.12-3=1.12;...

4.56+3/7+4.44+4/7 =(4.56+4.44)+(3/7+4/7) =9+1 =10 本题用到了数学计算中的加法交换律和结合律。

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