1. 直接写出得数。
$0.38 + 0.2 =$ $3.7 - 2.5 =$ $1 - 0.52 =$
$\frac{1}{5} + \frac{4}{5} =$ $1 - \frac{5}{8} =$ $\frac{3}{11} + \frac{7}{11} =$
$12 ÷ 1000 =$ $1.6 × 0.6 =$ $3 × 5.6 =$
$4.2 × 5 =$ $6 × 8.9 =$ $14 × 0.8 =$
$14.6 - 0.34 =$ $1000 × 0.13 =$ $13 - 1.3 =$
$0.7 + 6.8 =$ $6.5 + 3.8 =$ $0.7 - 0.07 =$

0.38 + 0.2 = 0.58
3.7 - 2.5 = 1.2
1 - 0.52 = 0.48
$\frac{1}{5} + \frac{4}{5} = 1$
$1 - \frac{5}{8} = \frac{3}{8}$
$\frac{3}{11} + \frac{7}{11} = \frac{10}{11}$
12 ÷ 1000 = 0.012
1.6 × 0.6 = 0.96
3 × 5.6 = 16.8
4.2 × 5 = 21
6 × 8.9 = 53.4
14 × 0.8 = 11.2
14.6 - 0.34 = 14.26
1000 × 0.13 = 130
13 - 1.3 = 11.7
0.7 + 6.8 = 7.5
6.5 + 3.8 = 10.3
0.7 - 0.07 = 0.63

2. 计算下列各题，能简算的要简算。
$2.8 × 0.4 + 3.8$ $(0.8 + 0.6) × 30$
$7.42 - 5.87 + 2.58 - 4.13$ $0.25 × 4.4$
$2.5 × 32 × 12.5$ $32.1 - 25.6 + 4.4$
$(9.6 - 0.69 × 2) + 4.11$ $2.5 × 3.7 + 6.3 × 2.5$

$2.8 × 0.4 + 3.8$
$=1.12 + 3.8$
$=4.92$
$(0.8 + 0.6) × 30$
$=0.8×30 + 0.6×30$
$=24 + 18$
$=42$
$7.42 - 5.87 + 2.58 - 4.13$
$=(7.42 + 2.58) - (5.87 + 4.13)$
$=10 - 10$
$=0$
$0.25 × 4.4$
$=0.25×(4 + 0.4)$
$=0.25×4 + 0.25×0.4$
$=1 + 0.1$
$=1.1$
$2.5 × 32 × 12.5$
$=2.5×(4×8)×12.5$
$=(2.5×4)×(8×12.5)$
$=10×100$
$=1000$
$32.1 - 25.6 + 4.4$
$=6.5 + 4.4$
$=10.9$
$(9.6 - 0.69 × 2) + 4.11$
$=(9.6 - 1.38) + 4.11$
$=8.22 + 4.11$
$=12.33$
$2.5 × 3.7 + 6.3 × 2.5$
$=2.5×(3.7 + 6.3)$
$=2.5×10$
$=25$