| 0.27+2.73= | 0.25÷2.5%= | 10-0.01= | 0.38-0.19= | 1-50%= |
× = | ÷ = | - + - = | - = | ×( -25%)= |
| 0.27+2.73=3, | 0.25÷2.5%=10, | 10-0.01=9.99, | 0.38-0.19=0.19, | 1-50%=0.5, |
× = , | ÷ = , | - + - =0, | - = , | ×( -25%)= . |
分析:根据小数、分数加减乘除的计算方法进行计算;
-
+
-
根据加法交换律和结合律进行计算.点评:口算时,注意运算符号和数据,然后再进一步计算.
×
=
÷
=
-
=
×(
-25%)=
,
,