| 用简便方法计算,并写出简算过程. 246+78.5+254+21.5 | 0.125×2.5×320 |
36×( - + ) | ×0.2+ ÷5. |
=(246+254)+(78.5+21.5),
=500+100,
=600;
(2)0.125×2.5×320
=0.125×2.5×80×4,
=(0.125×80)×(2.5×4),
=10×10,
=100;
(3)36×(
-
+
)=36×
-36×
+36×
,=24-9+4,
=19;
(4)
×0.2+
÷5=
××
+
×
,=(
+
)×
,=1×
,=
.分析:(1)可根据加法交换律及结合律计算;
(2)可将320拆分为80×4后,再据乘法交换律及结合律计算;
(3)(4)可根据乘法分配律计算;
点评:完成本题要注意分析式中数据的特点及内在联系,然后运用合适的方法计算.