题目内容
脱式计算.(能简算的要简算)
19.48×1.96-0.96×19.48
1
+2-3
10.75-(5
+4.2-4
)
3.12×[0.9+(1-0.3)÷0.1]
0.46×[10.8÷(4.5-2.8)](得数保留两位小数)
19.48×1.96-0.96×19.48
1
3 |
4 |
1 |
2 |
10.75-(5
4 |
5 |
2 |
3 |
3.12×[0.9+(1-0.3)÷0.1]
0.46×[10.8÷(4.5-2.8)](得数保留两位小数)
考点:整数、分数、小数、百分数四则混合运算
专题:运算顺序及法则
分析:(1)可根据乘法分配律计算.
(2)按从左到右的顺序先算加法,再算减法.
(3)可将式中的小数化成分数,先算括号中的加法与减法,再算括号外的减法.
(4)(5)先算乘除,再算加减,有括号的要先算括号里面的.
(2)按从左到右的顺序先算加法,再算减法.
(3)可将式中的小数化成分数,先算括号中的加法与减法,再算括号外的减法.
(4)(5)先算乘除,再算加减,有括号的要先算括号里面的.
解答:
解:(1)19.48×1.96-0.96×19.48
=(1.96-0.96)×19.48
=1×19.48
=19.48;
(2)1
+2-3
=3
-3
=
;
(3)10.75-(5
+4.2-4
)
=10.75-(5
+4
-4
)
=10.75-(10-4
)
=10
-4
=6
;
(4)3.12×[0.9+(1-0.3)÷0.1]
=3.12×[0.9+0.7÷0.1]
=3.12×[0.9+7]
=3.12×7.9
=24.648;
(5)0.46×[10.8÷(4.5-2.8)]
=0.46×[10.8÷1.7]
=0.46×
≈2.92.
=(1.96-0.96)×19.48
=1×19.48
=19.48;
(2)1
3 |
4 |
1 |
2 |
=3
3 |
4 |
1 |
2 |
=
1 |
4 |
(3)10.75-(5
4 |
5 |
2 |
3 |
=10.75-(5
4 |
5 |
1 |
5 |
2 |
3 |
=10.75-(10-4
2 |
3 |
=10
3 |
4 |
2 |
3 |
=6
1 |
12 |
(4)3.12×[0.9+(1-0.3)÷0.1]
=3.12×[0.9+0.7÷0.1]
=3.12×[0.9+7]
=3.12×7.9
=24.648;
(5)0.46×[10.8÷(4.5-2.8)]
=0.46×[10.8÷1.7]
=0.46×
108 |
17 |
≈2.92.
点评:完成此类题目要细心,当算式中同时含有中括号与小括号时,要先算小括号里面的,再算中括号里面的.
练习册系列答案
相关题目