题目内容
(2012?桐庐县)计算.
①92×13+28
②4.2÷1.5-0.36
③78×
④1÷
-
÷1
⑤
×5÷
×5
⑥2-
÷
⑦36×(
+
)
①92×13+28
②4.2÷1.5-0.36
③78×
| 3 |
| 79 |
④1÷
| 1 |
| 4 |
| 1 |
| 4 |
⑤
| 2 |
| 5 |
| 2 |
| 5 |
⑥2-
| 8 |
| 15 |
| 4 |
| 9 |
⑦36×(
| 1 |
| 6 |
| 2 |
| 3 |
分析:①②④⑥根据四则混合运算的运算顺序计算即可:先算乘除,再算加减;
③可先将78变为79-1后,根据乘法分配律计算;
⑤可根据乘法交换律计算;
⑦可根据乘法分配律计算.
③可先将78变为79-1后,根据乘法分配律计算;
⑤可根据乘法交换律计算;
⑦可根据乘法分配律计算.
解答:解:①92×13+28
=1196+28,
=1224;
②4.2÷1.5-0.36
=2.8-0.36,
=2.44;
③78×
=(79-1)×
,
=79×
-1×
,
=3-
,
=2
;
④1÷
-
÷1
=4-
,
=3
;
⑤
×5÷
×5
=
÷
×5×5,
=1×5×5,
=25;
⑥2-
÷
=2-
,
=
;
⑦36×(
+
)
=36×
+36×
,
=6+24,
=30.
=1196+28,
=1224;
②4.2÷1.5-0.36
=2.8-0.36,
=2.44;
③78×
| 3 |
| 79 |
=(79-1)×
| 3 |
| 79 |
=79×
| 3 |
| 79 |
| 3 |
| 79 |
=3-
| 3 |
| 79 |
=2
| 76 |
| 79 |
④1÷
| 1 |
| 4 |
| 1 |
| 4 |
=4-
| 1 |
| 4 |
=3
| 3 |
| 4 |
⑤
| 2 |
| 5 |
| 2 |
| 5 |
=
| 2 |
| 5 |
| 2 |
| 5 |
=1×5×5,
=25;
⑥2-
| 8 |
| 15 |
| 4 |
| 9 |
=2-
| 6 |
| 5 |
=
| 4 |
| 5 |
⑦36×(
| 1 |
| 6 |
| 2 |
| 3 |
=36×
| 1 |
| 6 |
| 2 |
| 3 |
=6+24,
=30.
点评:完成本题要注意分析式中数据的特点,运用合适的方法进行计算.
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