| 直接写出得数. 0.44+ + +0.6 | +2 ×2 -2 ÷![]() | (4 -2 )÷(1 +2.4) |
| 48200-156×720÷39 | (3.06÷0.25+2.76)×0.2 | [3 ÷(3-2.4× )]×0.2. |
+
+0.6,=0.44+0.4+0.56+0.6,
=(0.44+0.56)+(0.4+0.6),
=1+1,
=2;
(2)
+2
×2
-2
÷
,=
+
-3,=5-3,
=2;
(3)(4
-2
)÷(1
+2.4),=2
÷3
,=
×
,=
;(4)48200-156×720÷39,
=48200-112320÷39,
=48200-2880,
=45320;
(5)(3.06÷0.25+2.76)×0.2,
=(12.24+2.76)×0.2,
=15×0.2,
=3;
(6)[3
÷(3-2.4×
)]×0.2,=[3
÷(3-
)]×0.2,=[3
÷
]×0.2,=
×
,=
.分析:(1)先把分数化成小数,然后再运用加法结合律简算;
(2)同时运算乘法和除法,再算加法,最后算减法;
(3)同时运算两个小括号里面的减法和加法,最后算括号外的除法;
(4)先算乘法,再算除法,最后算减法;
(5)先算小括号里面的除法,再算小括号里面的加法,最后算括号外的乘法;
(6)先算小括号里面的乘法,再算小括号里面的减法,然后算中括号里面的除法,最后算括号外的乘法.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.