Question

直接写出得数．

9 10 ×40=	3 4 - 1 8 =	8 15 × 5 8 =	2× 11 21 =	24× 1 3 =
2 11 ×22=	18× 1 6 =	2 9 × 3 7 =	4 9 × 1 10 =	8 25 × 5 4 =

Answer 1

分析：①③⑤⑥⑦⑧⑨⑩注意约分计算；②通分计算；④用整数与分子相乘的积做分子，分母不变．

解答：解：①

9

10

×40=36；    ②

3

4

-

1

8

=

5

8

；         ③

8

15

×

5

8

=

1

3

；         ④2×

11

21

=

22

21

；         ⑤24×

1

3

=8；
⑥

2

11

×22=4；         ⑦18×

1

6

=3；         ⑧

2

9

×

3

7

=

2

21

；        ⑨

4

9

×

1

10

=

2

45

；        ⑩

8

25

×

5

4

=

2

5

．

点评：此题考查了通过约分、通分等进行分数计算的能力．