题目内容

口算．
1
3
×
3
5
=
5÷
1
3
=
2
5
×10=
0÷
2
3
=
2
5
+
3
5
=
3
8
÷
1
2
=		 1-
4
7
=
5
7
-
3
7
=
1
5
+
1
3
=		 1.8×3=
分析：分数乘法：分子相乘的积作为分子，分母相乘的积作为分母；分数除法：除以一个数等于乘这个数的倒数；同分母分数相加减，分母不变，分子相加减；异分母分数相加减，先通分化成同分母的分数，再计算．
解答：解：
1
3
×
3
5
=
1
5
，
5÷
1
3
=15，
2
5
×10=4，
0÷
2
3
=0，
2
5
+
3
5
=1，
3
8
÷
1
2
=
3
4
，		 1-
4
7
=
3
7
，
5
7
-
3
7
=
2
7
，
1
5
+
1
3
=
8
15
，		 1.8×3=5.4．
故答案为：
1
5
，15，4，0，1，
3
4
，
3
7
，
2
7
，
8
15
，5.4．
点评：本题考查了分数的基本运算，注意运算的法则，把结果化成最简分数．
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