Question

直接寫得數
3.2+7=10.2                               

8

3

÷6=

4

9

                          40×（

4

5

-

5

8

）=7
12×40%=4.8                              50-25%=49.75                     20×18%=3.6

2

9

×

2

9

÷

2

9

=

2

9

                              5-

1

5

÷5=4

24

25

．

Answer 1

分析：①注意數位對齊；②把除法改為乘法，約分計算；③先算括號內的，再算括號外的；④⑤⑥把百分數化為小數，再計算；⑦可調整一下運算順序，使計算簡便；⑧先算除法，再算減法．

解答：解：
3.2+7=10.2                               

8

3

÷6=

4

9

                          40×（

4

5

-

5

8

）=7
12×40%=4.8                              50-25%=49.75                     20×18%=3.6

2

9

×

2

9

÷

2

9

=

2

9

                              5-

1

5

÷5=4

24

25

．

點評：此題考查了小數、分數的運算，注意小數點對齊以及運算順序，是解題關鍵．