口算
1-
7
9
÷
7
8
=
0.24×0.5= 0.52+0.12= 1.25×8÷1.25×8=
3
5
×
2
3
×30=
3
8
+
5
8
-
5
8
+
3
8
=
4-
3
7
-
4
7
=
2÷5÷
4
5
×
2
3
=
分析:①先算除法,再算減法;②先算24×5,然后在得數(shù)中從后向前數(shù)出三位,點上小數(shù)點;③先算乘方,再算加法;④⑧按運算順序從左往右依次運算;⑤約分計算;⑥運用加法交換律與結(jié)合律簡算;⑦運用減法的性質(zhì)簡算.
解答:解:1-
7
9
÷
7
8
=
1
9
;         0.24×0.5=0.12;          0.52+0.12=0.26;       1.25×8÷1.25×8=64;
3
5
×
2
3
×30=12;          
3
8
+
5
8
-
5
8
+
3
8
=
3
4
;          4-
3
7
-
4
7
=3;             2÷5÷
4
5
×
2
3
=
1
3
;
故答案為:
1
9
,0.12,0.26,64,12,
3
4
,3,
1
3
點評:考查了四則混合運算,注意運算順序和運算法則,靈活運用所學的運算定律簡便計算.
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