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6.36-2.22+2.64-0.78
12.5×(8-0.8)×4
1.25×6.4×0.25×0.2
7.5×10-7.5×6.5+7.5×0.5
(2.6×1.5+1.1)-2.5×8
8÷[(40.75-9.5)×0.4]-0.6.

解:(1)6.36-2.22+2.64-0.78
=(6.36+2.64)-(2.22+0.78)
=9-3
=6;

(2)12.5×(8-0.8)×4
=(12.5×8-12.5×0.8)×4
=(100-10)×4
=90×4
=360;

(3)1.25×6.4×0.25×0.2
=1.25×8×0.8×0.25×0.2
=(1.25×8)×0.8×(0.25×0.2)
=10×0.8×0.05
=10×(0.8×0.05)
=10×0.04
=0.4;

(4)7.5×10-7.5×6.5+7.5×0.5
=7.5×(10-6.5+0.5)
=7.5×4
=30;

(5)(2.6×1.5+1.1)-2.5×8
=(3.9+1.1)-(2.5×4)×2
=5-10×2,
=5-20
=-15;

(6)8÷[(40.75-9.5)×0.4]-0.6
=8÷[31.25×0.4]-0.6
=8÷[(31+0.25)×0.4]-0.6
=8÷[31×0.4+0.25×0.4]-0.6
=8÷[12.4+0.1]-0.6
=8÷12.5-0.6
=0.64-0.6
=0.04.
分析:(1)运用加法交换律与结合律简算;
(2)运用乘法分配律简算;
(3)把6.4看作8×0.8,运用乘法结合律简算;
(4)运用乘法结合律简算;
(5)先算括号内的乘法和括号外的乘法,再算括号内的加法,最后算括号外的减法;
(6)先算小括号内的,再算中括号内的,然后算括号外的除法,最后算括号外的减法.
点评:解答此题,注意运算顺序,以及运用运算定律进行简算.
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