| 直接写数对又快. 97-28= | ÷ = | × = | × = |
| 2.5×4= | + = | 8÷80%= | × ÷ × = |
| 解:97-28=69, | ÷ = , | × = , | × = , |
| 2.5×4=10, | + = , | 8÷80%=10, | × ÷ × = . |
分析:把8÷80%改写成8÷0.8,再计算;
×
÷
×
改写成
×
×4×
,再利用乘法结合律简算;异分母分数相加减:先通分成同分母分数,再相加减;
分数除法:先改写成被除数乘除数的倒数,能约分的先约分,再计算;
分数乘法:能约分的先约分,再计算.
点评:本题是基本的计算题目,计算时要细心,注意运算符号和数的特点.
÷
=
×
=
×
=
,
,
,
.