题目内容
脱式计算:(能简算的要简算).
①5.6×0.7+0.2×5.6+0.56
②1375+450÷18×25
③
÷7+
×
④91×
+9÷17-1÷17×100.
①5.6×0.7+0.2×5.6+0.56
②1375+450÷18×25
③
| 9 |
| 17 |
| 1 |
| 7 |
| 8 |
| 17 |
④91×
| 1 |
| 17 |
分析:①先把0.56分解成5.6×0.1,再运用乘法分配律简算;
②先算除法,再算乘法,最后算加法;
③先把除法变成乘法,再运用乘法分配律简算;
④先把除法变成乘法,再运用乘法分配律简算.
②先算除法,再算乘法,最后算加法;
③先把除法变成乘法,再运用乘法分配律简算;
④先把除法变成乘法,再运用乘法分配律简算.
解答:解:①5.6×0.7+0.2×5.6+0.56,
=5.6×0.7+0.2×5.6+5.6×0.1,
=5.6×(0.7+0.2+0.1),
=5.6×1,
=5.6;
②1375+450÷18×25,
=1375+25×25,
=1375+625,
=2000;
③
÷7+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
④91×
+9÷17-1÷17×100,
=91×
+9×
-100×
,
=(91+9-100)×
,
=0×
,
=0.
=5.6×0.7+0.2×5.6+5.6×0.1,
=5.6×(0.7+0.2+0.1),
=5.6×1,
=5.6;
②1375+450÷18×25,
=1375+25×25,
=1375+625,
=2000;
③
| 9 |
| 17 |
| 1 |
| 7 |
| 8 |
| 17 |
=
| 9 |
| 17 |
| 1 |
| 7 |
| 1 |
| 7 |
| 8 |
| 17 |
=(
| 9 |
| 17 |
| 8 |
| 17 |
| 1 |
| 7 |
=1×
| 1 |
| 7 |
=
| 1 |
| 7 |
④91×
| 1 |
| 17 |
=91×
| 1 |
| 17 |
| 1 |
| 17 |
| 1 |
| 17 |
=(91+9-100)×
| 1 |
| 17 |
=0×
| 1 |
| 17 |
=0.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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