| 41×101 | 7.8+ +2.2+![]() | 72×( + ) |
| 2.5×1.25×32 | [1-( + )]÷![]() | ( - )÷( + ) |
=41×100+41×1,
=4100+41,
=4141;
(2)7.8+
+2.2+
,=(7.8+2.2)+(
),=10+1,
=11;
(3)72×(
+
),=72×
+72×
,=27+32,
=59;
(4)2.5×1.25×32,
=(2.5×4)×(1.25×8),
=10×10,
=100;
(5)[1-(
+
)]÷
,=[1-
]÷
,=
,=2;
(6)(
-
)÷(
+
),=
,=
.分析:(1)(3)运用乘法分配律解答,
(2)运用加法交换律和结合律解答,
(4)化32=4×8,再运用乘法交换律和结合律解答,
(5)(6)依据四则混合运算顺序:先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的顺序解答.
点评:本题考查知识点:(1)正确选择并运用简便算法解决问题,(2)依据四则运算顺序正确进行计算.