1. 直接写出得数。
$\begin{array}{l} 6 4 + 2 0 = \\ 8 6 - 2 6 = \\ \end{array}$$ $$\begin{array}{l} 1 2 0 - 5 0 = \\ 4 5 0 - 2 3 0 = \\ \end{array}$$ $$\begin{array}{l} 8 4 0 - 4 0 0 = \\ 6 3 0 - 2 1 0 = \\ \end{array}$$ $$\begin{array}{l} 6 3 0 - 1 3 0 = \\ 1 0 0 0 - 3 0 0 = \\ \end{array}$

1. 84 70 440 500 60 220
420 700

2. 先说说十位、百位各怎样减，再计算。

2. 说说及竖式略。71 191 291
195 592 118 262 73

3. 列竖式计算。
$2 6 7 - 5 8 =$$ $$5 5 8 - 3 4 1 =$$ $$4 2 4 - 3 1 5 =$
$1 2 5 - 3 6 =$$ $$9 6 1 - 4 7 3 =$$ $$8 5 2 - 1 4 3 =$

3. 209 $\boldsymbol{\begin{array}{r} \dot{267}\\ -\ \ 58\\ \hline 209\end{array}}$ 217 $\boldsymbol{\begin{array}{r} 558\\ -341\\ \hline 217\end{array}}$

109 $\boldsymbol{\begin{array}{r} \dot{424}\\ -315\\ \hline 109\end{array}}$ 89 $\boldsymbol{\begin{array}{r} \dot{1}\dot{2}5\\ -\ \ 36\\ \hline 89\end{array}}$

488 $\boldsymbol{\begin{array}{r} \dot{9}\dot{6}1\\ -473\\ \hline 488\end{array}}$ 709 $\boldsymbol{\begin{array}{r} \dot{852}\\ -143\\ \hline 709\end{array}}$