| 计算能简算的要用简便方法计算. 25×1.25×32×1.7=________; | 78-4.5+22- =________; |
| 5400-2940÷28×27=________; | 20×( + - )=________; |
( )×5×4=________; | 10÷[4-( ÷ + )]=________. |

分析:(1)把32看做8×4,运用乘法交换律与结合律简算;
(2)把
化为小数0.5,运用加法交换律与结合律简算;(3)先算除法合乘法,再算减法;
(4)(5)运用乘法分配律简算;
(6)先算小括号内的除法,原式变为10÷[4-(2+
)],中括号内运用减法的性质计算,最后算括号外的除法.解答:(1)25×1.25×32×1.7,
=25×1.25×8×4×1.7,
=(25×4)×(1.25×8)×1.7,
=100×10×1.7,
=1700;
(2)78-4.5+22-
,=78-4.5+22-0.5,
=(78+22)-(4.5+0.5),
=100-5,
=95;
(3)5400-2940÷28×27,
=5400-2940÷28×27,
=5400-2835,
=2565;
(4)20×(
+
-
),=20×
+20×
-20×
,=16+14-15,
=15;
(5)(
)×5×4,=
×5×4+
×5×4,=16+5,
=21;
(6)10÷[4-(
÷
+
)],=10÷[4-(
×
+
)],=10÷[4-(2+
)],=10÷[4-2-
],=10÷
,=10×
,=
.故答案为:1700,95,2565,15,21,
.点评:完成此题应注意运算顺序和运算法则,灵活运用所学的运算律简便计算.