考点:整数、分数、小数、百分数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算减法和乘法,再算括号里面的除法,再算括号外面的除法,最后算加法;
(2)把除法改为乘法,进一步利用乘法交换律与结合律简算;
(3)先算减法和加法,再按照从左到右的顺序计算;
(4)利用乘法分配律简算;
(5)先算乘法和除法,再算减法;
(6)先算小括号里面的减法,再算乘除,最后算减法;
解答:
解:(1)11
÷[( 7.35-5
)÷1.02]+82.5×
=11
÷[2
÷1.02]+33
=11
÷[
×
]+33
=
×
=5;
(2)0.25×1.25÷
=0.25×1.25×32
=0.25×4×(1.25×8)
=1×10
=10;
(3)(
-
)×120%÷(2
+1.5 )÷
=
×
÷3
÷
=
×
×
×3
=
;
(4)7.3×
+0.4×3.7-40%
=(7.3+3.7-1)×0.4
=10×0.4
=4;
(5)69×18.5-15÷
=1276.5-15×
=1276.5-277.5
=999;
(6)6
-6.3×[(10-3
)÷6.4]÷1
=6
-6.3×[6.6÷6.4]÷1
=6
-6.3×
×
=6.25-2.8875
=3.3625.
点评:混合运算的关键是抓住运算顺序,正确按运算顺序计算,适当利用运算定律简算.