1. $\frac{3}{5}+\frac{2}{5}=$ $\frac{7}{9}-\frac{5}{9}=$ $\frac{3}{11}+\frac{3}{11}+\frac{3}{11}=$
$\frac{1}{5}\times5=$ $\frac{3}{8}\times2=$ $\frac{8}{13}-\frac{2}{13}-\frac{2}{13}=$
$\frac{1}{5}\times5=$ $\frac{3}{8}\times2=$ $\frac{8}{13}-\frac{2}{13}-\frac{2}{13}=$
答案
2. 计算。
$\begin{array}{r}38\\\times27\\\hline\end{array}$ $\begin{array}{r}63\\\times29\\\hline\end{array}$ $\begin{array}{r}54\\\times78\\\hline\end{array}$ $\begin{array}{r}43\\\times67\\\hline\end{array}$
$\begin{array}{r}38\\\times27\\\hline\end{array}$ $\begin{array}{r}63\\\times29\\\hline\end{array}$ $\begin{array}{r}54\\\times78\\\hline\end{array}$ $\begin{array}{r}43\\\times67\\\hline\end{array}$
答案
3. 计算下列各题。
$25\times9\div3$ $432\div8\times15$ $(900 - 180)\div90$
$25\times9\div3$ $432\div8\times15$ $(900 - 180)\div90$
答案
4. 在$\square$里填上合适的数。
$82\times95$
$= 82\times(90+\square)$
$= 82\times90 + 82\times\square$
$=\square+\square$
$=\square$
$82\times95$
$= 82\times(\square - 5)$
$= 82\times\square- 82\times5$
$=\square-\square$
$=\square$
$82\times95$
$= 82\times(90+\square)$
$= 82\times90 + 82\times\square$
$=\square+\square$
$=\square$
$82\times95$
$= 82\times(\square - 5)$
$= 82\times\square- 82\times5$
$=\square-\square$
$=\square$
答案
5. 求各图形表示的数。
$20\times▲ + 500 = 660$ $70\times□ - 200 = 430$
$5\times(10 -●)= 20$ $5\times(○ - 10)= 120$
$20\times▲ + 500 = 660$ $70\times□ - 200 = 430$
$5\times(10 -●)= 20$ $5\times(○ - 10)= 120$
答案
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