Question

直接写得数． 5 8 × 2 5 =	4 21 × 7 8 =	0.9× 3 4 =
39× 1 13 =	8 15 × 9 10 =	80× 3 4 × 1 3 =

Answer 1

分析：第③题，把小数转化为分数，这几个题目都属于分数乘分数的计算，约分即可．

解答：解：

5

8

×

2

5

=

1

4

；                     

4

21

×

7

8

=

1

6

；                    0.9×

3

4

=

27

40

；   
39×

1

13

=3；                        

8

15

×

9

10

=

12

25

；                  80×

3

4

×

1

3

=20．

点评：解答此题，主要通过约分计算来完成．