24× = | 1÷ = | ×18÷3= |
÷ = | ( - )× = | × ÷ × = |
1- ÷24×0= | ( - )×30= | ( ×( = |
解:24× =4, | 1÷ =![]() | ×18÷3= , |
÷ = , | ( - )× = , | × ÷ × = , |
1- ÷24×0=1, | ( - )×30=19, | ( ×( =0. |
分析:分数乘法:分子相乘的积做分子,分母相乘的积做分母;
分数除法:除以一个数等于乘这个数的倒数;
×
÷
×
先把除法变成乘法,再运用乘法结合律简算;(
-
)×30运用乘法分配律简算;其它混合运算,按照运算顺序逐步计算即可.
点评:口算题目,要求快速准确,能用简便方法的要用简便方法.
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÷24×0=
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