1. 直接写出得数。
$9.9 + 0.01 =$ $5 - 2.3 =$ $0.25 + 1.21 =$
$0 ÷ 120 =$ $0.6 - 0.47 =$ $0.95 - 0.5 =$
$8.2 + 1.5 =$ $0.76 + 0.24 =$ $32.8 + 8 =$
$89 - 8.3 =$ $10.3 + 0.8 =$ $5.9 + 4.8 =$
$32 + 24.7 =$ $3.6 + 0.8 =$ $8.4 - 0.7 =$
$2.2 - 1.3 =$ $12.6 + 4.8 =$ $9.7 + 10.4 =$

$9.9 + 0.01 = 9.91$
$5 - 2.3 = 2.7$
$0.25 + 1.21 = 1.46$
$0 ÷ 120 = 0$
$0.6 - 0.47 = 0.13$
$0.95 - 0.5 = 0.45$
$8.2 + 1.5 = 9.7$
$0.76 + 0.24 = 1$
$32.8 + 8 = 40.8$
$89 - 8.3 = 80.7$
$10.3 + 0.8 = 11.1$
$5.9 + 4.8 = 10.7$
$32 + 24.7 = 56.7$
$3.6 + 0.8 = 4.4$
$8.4 - 0.7 = 7.7$
$2.2 - 1.3 = 0.9$
$12.6 + 4.8 = 17.4$
$9.7 + 10.4 = 20.1$

2. 列竖式计算。
$23.1 + 5.41 =$ $7.12 + 1.35 =$ $6.75 - 1.25 =$
$3.89 - 0.9 =$ $5 + 2.34 =$ $16 - 3.21 =$

23.10
+ 5.41
-------
28.51
$23.1 + 5.41 = 28.51$
7.12
+ 1.35
-------
8.47
$7.12 + 1.35 = 8.47$
6.75
1.25
-------
5.50
$6.75 - 1.25 = 5.5$
3.89
0.90
-------
2.99
$3.89 - 0.9 = 2.99$
5.00
+ 2.34
-------
7.34
$5 + 2.34 = 7.34$
16.00
3.21
-------
12.79
$16 - 3.21 = 12.79$

3. 判断，对的画“√”，错的画“×”，并改正。
(1)

$\begin{array}{r} 6.38 \\ + 12.5 \\ \hline 76.3 \end{array}$$ ($ $)改正：(2)$\begin{array}{r} 6.68 \\ - 4 \\ \hline 6.64 \end{array}$$ ( )
改正：

(1) ×
改正：
$\begin{array}{r} 6.38 \\ + 12.50 \\ \hline 18.88 \end{array}$
(2) ×
改正：
$\begin{array}{r} 6.68 \\ - \ \ 4.00 \\ \hline 2.68 \end{array}$