题目内容
脱式计算下面各题(能简算的要用简便方法计算,并写出简算过程).
450÷18×25+173. | 670+65÷3×
|
|
38-12×6÷16. |
分析:(1)先算除法,再算乘法,最后算加法;
(2)先把除法变成乘法,再运用乘法结合律简算;
(3)先算乘法,再算减法,最后算加法;
(4)先算乘法,再算除法,最后算减法.
(2)先把除法变成乘法,再运用乘法结合律简算;
(3)先算乘法,再算减法,最后算加法;
(4)先算乘法,再算除法,最后算减法.
解答:解:(1)450÷18×25+173,
=25×25+173,
=625+173,
=798;
(2)670+65÷3×
,
=670+65×(
×
),
=670+65×
,
=670+13,
=683;
(3)
-
×
+57,
=
-
+57,
=
+57,
=57
;
(4)38-12×6÷16,
=38-72÷16,
=38-4.5,
=33.5.
=25×25+173,
=625+173,
=798;
(2)670+65÷3×
3 |
5 |
=670+65×(
1 |
3 |
3 |
5 |
=670+65×
1 |
5 |
=670+13,
=683;
(3)
5 |
8 |
1 |
6 |
4 |
5 |
=
5 |
8 |
2 |
15 |
=
59 |
120 |
=57
59 |
120 |
(4)38-12×6÷16,
=38-72÷16,
=38-4.5,
=33.5.
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.
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