算一算。
$\begin{array}{r} 34 \\ ×21 \\ \hline \end{array}$ $\begin{array}{r} 42 \\ ×12 \\ \hline \end{array}$ $\begin{array}{r} 33 \\ ×23 \\ \hline \end{array}$

$\begin{array}{r} 24 \\ ×53 \\ \hline \end{array}$ $\begin{array}{r} 51 \\ ×26 \\ \hline \end{array}$ $\begin{array}{r} 62 \\ ×25 \\ \hline \end{array}$

1. $34×21=714$
2. $42×12=504$
3. $33×23=759$
4. $24×53=1272$
5. $51×26=1326$
6. $62×25=1550$

用竖式计算。
$35×12=$
$17×18=$
$44×14=$
$56×28=$
$43×19=$
$28×77=$

1. $35×12=420$
2. $17×18=306$
3. $44×14=616$
4. $56×28=1568$
5. $43×19=817$
6. $28×77=2156$