用递等式计算:(能简便的就用简便方法计算,并写出主要计算过程)(1)38.78-19.59+41.22-30.41(2)2.7

用递等式计算:(能简便的就用简便方法计算,并写出主要计算过程)(1)38.78-19.59+41.22-30.41(2)2.74×4.86+4.86×6.26+4.86(3)0.08×(12.5+2.5)×0.1(4)25.92+(10.1-14.5×0.2)(5)0.487×12.5÷48.7(6)(8.16+2.09)÷[(10.3-9.3)÷0.4].


(1)38.78-19.59+41.22-30.41,
=38.78+41.22-19.59-30.41,
=(38.78+41.22)-(19.59+30.41),
=80-50,
=30;

(2)2.74×4.86+4.86×6.26+4.86,
=(2.74+6.26+1)×4.86,
=10×4.86,
=48.6;

(3)0.08×(12.5+2.5)×0.1,
=(0.08×12.5+0.08×2.5)×0.1,
=(1+0.2)×0.1,
=1.2×0.1,
=0.12;

(4)25.92+(10.1-14.5×0.2),
=25.92+(10.1-2.9),
=25.92+7.2,
=33.12;

(5)0.487×12.5÷48.7,
=0.487÷48.7×12.5,
=0.01×12.5,
=0.125;

(6)(8.16+2.09)÷[(10.3-9.3)÷0.4],
=10.25÷[1÷0.4],
=10.25÷2.5,
=4.1.

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