直接写得数. + =________; | 18× =________; | × =________; |
1× =________; | - =________; | ×21=________; |
× =________; | ×6=________; | × =________; |
×9=________; | × =________; | 2- =________. |
12

15

2
1
分析:根据分数加减法和分数乘法的计算方法进行计算即可.
解答:
+
=
;18×
=12;
×
=
;1×
=
;
-
=
;
×21=15;
×
=
;
×6=
;
×
=
;
×9=2;
×
=
;2-
=1
.点评:分数的口算,加减法的要先通分再计算,乘法的先约分再计算,结果都要化成最简分数.