题目内容
【题目】口算.
21%+5% ÷4 8π
+
125×8
×
+
﹣
÷
8÷64
×
7π
+
×
13÷26
﹣
67%﹣24% 99×5
×
×
÷
100÷25
×
×
×
÷
667+34
÷
÷
1263﹣163
÷
×
÷
÷
98%﹣55%
÷
×
15.7÷3.14
﹣
×
÷
÷
+
÷
×
÷
×
6.28÷π 0×
21÷5
×
÷
39×
3π 66×10
0÷875 1﹣﹣
(
﹣
)×12
×
+
×
3﹣
﹣
【答案】26%,,25.12,
,1000,
,
,
,
,
,
,21.98,
,
,
,
,43%,495,
,
,
,4,
,
,
,
,700,
,
,1100,
,
,
,8,43%,
,
,5,
,
,
,6,
,
,
,
,
,2,0,
,
,
,12,9.42,660,0,
,1,
,2
【解析】
试题分析:根据所给的题目的特点,可分为以下几类:一类是分数加、减法,如果是同分母的分数相加减,分母不变,分子相加减,如果是异分母的分数相加减,先化成同分母的分数,再计算;二类是分数乘法,分数乘整数时,用分数的分子和整数相乘的积做分子,分母不变,(能约分要在计算中先约分 )分数乘分数,用分子相乘的积做分子,分母相乘的积做分母,能约分的要约成最简分数(在计算中约分);三类是分数除法,即除以一个数等于乘这个数的倒数.
解:
21%+5%=26% ÷4=
8π=25.12
+
=
125×8=1000
×
=
+
=
﹣
=
÷
=
8÷64=
×
=
7π=21.98
+
=
×
=
13÷26=
﹣
=
67%﹣24%=43% 99×5=495
×
=
×
=
÷
=
100÷25=4
×
=
×
=
×
=
÷
=
667+34=700
÷
=
÷
=
1263﹣163=1100
÷
=
×
=
÷
=
÷
=8 98%﹣55%=43%
÷
=
×
=
15.7÷3.14=5
﹣
=
×
=
÷
=
÷
=6
+
=
÷
=
×
=
÷
=
×
=
6.28÷π=2 0×
=0 21÷5=
×
=
÷
=
39×
=12 3π=3×3.14=9.42 66×10=660
0÷875=0 1﹣﹣
=
(
﹣
)×12=1
×
+
×
=
3﹣
﹣
=2
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