题目内容
(2009?资中县)用递等式计算(能简算的请简算)
①46.3-10.4+3.7-9.6
②18×7.9+0.18×210
③
÷23+
×
④1236+450÷18×15
⑤(
+
)÷
-
⑥36÷[
+(
-
)].
①46.3-10.4+3.7-9.6
②18×7.9+0.18×210
③
| 8 |
| 17 |
| 1 |
| 23 |
| 9 |
| 17 |
④1236+450÷18×15
⑤(
| 1 |
| 2 |
| 1 |
| 3 |
| 5 |
| 12 |
| 17 |
| 18 |
⑥36÷[
| 5 |
| 6 |
| 5 |
| 8 |
| 1 |
| 3 |
分析:①运用加法交换律与结合律以及减法的性质简算;
②根据数字特点,把原式变为18×7.9+18×2.1,运用乘法分配律简算;
③把除法变为乘法,④先算除法和乘法,再算加法;
⑤先算括号内的,再算括号外的除法,最后算减法;
⑥先算小括号内的,再算中括号内的,最后算括号外的.
②根据数字特点,把原式变为18×7.9+18×2.1,运用乘法分配律简算;
③把除法变为乘法,④先算除法和乘法,再算加法;
⑤先算括号内的,再算括号外的除法,最后算减法;
⑥先算小括号内的,再算中括号内的,最后算括号外的.
解答:解:①46.3-10.4+3.7-9.6,
=46.3+3.7-(10.4+9.6),
=50-20,
=30;
②18×7.9+0.18×210,
=18×7.9+18×2.1,
=(7.9+2.1)×18,
=10×18,
=180;
③
÷23+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
④1236+450÷18×15,
=1236+25×15,
=1236+375,
=1611;
⑤(
+
)÷
-
,
=
×
-
,
=2-
,
=1
;
⑥36÷[
+(
-
)],
=36÷[
+
],
=36÷
,
=36×
,
=32.
=46.3+3.7-(10.4+9.6),
=50-20,
=30;
②18×7.9+0.18×210,
=18×7.9+18×2.1,
=(7.9+2.1)×18,
=10×18,
=180;
③
| 8 |
| 17 |
| 1 |
| 23 |
| 9 |
| 17 |
=
| 8 |
| 17 |
| 1 |
| 23 |
| 1 |
| 23 |
| 9 |
| 17 |
=(
| 8 |
| 17 |
| 9 |
| 17 |
| 1 |
| 23 |
=1×
| 1 |
| 23 |
=
| 1 |
| 23 |
④1236+450÷18×15,
=1236+25×15,
=1236+375,
=1611;
⑤(
| 1 |
| 2 |
| 1 |
| 3 |
| 5 |
| 12 |
| 17 |
| 18 |
=
| 5 |
| 6 |
| 12 |
| 5 |
| 17 |
| 18 |
=2-
| 17 |
| 18 |
=1
| 1 |
| 18 |
⑥36÷[
| 5 |
| 6 |
| 5 |
| 8 |
| 1 |
| 3 |
=36÷[
| 5 |
| 6 |
| 7 |
| 24 |
=36÷
| 9 |
| 8 |
=36×
| 8 |
| 9 |
=32.
点评:此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或性质进行简便计算.
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