题目内容
脱式计算. (1)100-91÷13 |
(2)(100-91)÷13 | (3)7.73-2.3÷0.5×0.8 | |||||||||||
(4)(1-
|
(5)
|
分析:(1)先算除法,再算减法;
(2)先算小括号里面的减法,再算括号外的除法;
(3)先算除法,再算乘法,最后算减法;
(4)先算小括号里面的乘法,再算小括号里面的减法,最后算括号外的除法;
(5)先算小括号里面的减法,再算中括号里面的除法,最后算括号外的除法.
(2)先算小括号里面的减法,再算括号外的除法;
(3)先算除法,再算乘法,最后算减法;
(4)先算小括号里面的乘法,再算小括号里面的减法,最后算括号外的除法;
(5)先算小括号里面的减法,再算中括号里面的除法,最后算括号外的除法.
解答:解:(1)100-91÷13,
=100-7,
=93;
(2)(100-91)÷13,
=9÷13,
=
;
(3)7.73-2.3÷0.5×0.8,
=7.73-4.6×0.8,
=7.73-3.68,
=4.05;
(4)(1-
×
)÷
,
=(1-
)÷
,
=
÷
,
=
;
(5)
÷[(
-
)÷5],
=
÷[
÷5],
=
÷
,
=
.
=100-7,
=93;
(2)(100-91)÷13,
=9÷13,
=
9 |
13 |
(3)7.73-2.3÷0.5×0.8,
=7.73-4.6×0.8,
=7.73-3.68,
=4.05;
(4)(1-
4 |
5 |
3 |
5 |
9 |
25 |
=(1-
12 |
25 |
9 |
25 |
=
13 |
25 |
9 |
25 |
=
13 |
9 |
(5)
3 |
4 |
2 |
3 |
1 |
6 |
=
3 |
4 |
1 |
2 |
=
3 |
4 |
1 |
10 |
=
15 |
2 |
点评:四则混合运算的顺序:1、如果是同一级运算,一般按从左往右依次进行计算;2、如果既有加减、又有乘除法,先算乘除法、再算加减;3、如果有括号,先算括号里面的.

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