题目内容
(2012?济南模拟)脱式计算,怎样简便就怎样算.
1485+290÷58×16
×[0.75-(
-
)]
4.2-1.38+5.8-3.62
24×
+76÷5
80.5×99+80.5
(
-0.75)÷(
-0.4)
0.7÷[(
-
)×24].
1485+290÷58×16
8 |
9 |
7 |
16 |
1 |
4 |
4.2-1.38+5.8-3.62
24×
1 |
5 |
80.5×99+80.5
(
5 |
6 |
2 |
3 |
0.7÷[(
5 |
6 |
1 |
4 |
分析:(1)先算除法,再算乘法,最后算加法;
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
(3)运用加法结合律,以及连续减去两个数等于减去这两个数的和简算;
(4)先把除法变成乘法,再运用乘法分配律简算;
(5)运用乘法分配律简算;
(6)先同时运算小括号里面的减法,再算括号外的除法;
(7)先把中括号里面的运算运用乘法分配律简算,再算括号外的除法.
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
(3)运用加法结合律,以及连续减去两个数等于减去这两个数的和简算;
(4)先把除法变成乘法,再运用乘法分配律简算;
(5)运用乘法分配律简算;
(6)先同时运算小括号里面的减法,再算括号外的除法;
(7)先把中括号里面的运算运用乘法分配律简算,再算括号外的除法.
解答:解:(1)1485+290÷58×16,
=1485+5×16,
=1485+80,
=1565;
(2)
×[0.75-(
-
)],
=
×[0.75-
],
=
×
,
=
;
(3)4.2-1.38+5.8-3.62,
=(4.2+5.8)-(1.38+3.62),
=10-5,
=5;
(4)24×
+76÷5,
=24×
+76×
,
=(24+76)×
,
=100×
,
=20;
(5)80.5×99+80.5,
=80.5×(99+1),
=80.5×100,
=8050;
(6)(
-0.75)÷(
-0.4),
=
÷
,
=
;
(7)0.7÷[(
-
)×24],
=0.7÷[
×24-
×24],
=0.7÷[20-6],
=0.7÷14,
=0.05.
=1485+5×16,
=1485+80,
=1565;
(2)
8 |
9 |
7 |
16 |
1 |
4 |
=
8 |
9 |
3 |
16 |
=
8 |
9 |
9 |
16 |
=
1 |
2 |
(3)4.2-1.38+5.8-3.62,
=(4.2+5.8)-(1.38+3.62),
=10-5,
=5;
(4)24×
1 |
5 |
=24×
1 |
5 |
1 |
5 |
=(24+76)×
1 |
5 |
=100×
1 |
5 |
=20;
(5)80.5×99+80.5,
=80.5×(99+1),
=80.5×100,
=8050;
(6)(
5 |
6 |
2 |
3 |
=
1 |
12 |
4 |
15 |
=
5 |
16 |
(7)0.7÷[(
5 |
6 |
1 |
4 |
=0.7÷[
5 |
6 |
1 |
4 |
=0.7÷[20-6],
=0.7÷14,
=0.05.
点评:考查了运算定律与简便运算,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简便计算.
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