1. 直接写出得数。
$3.2×0.4=$
$1.2×0.7=$
$0.125×0.8=$
$2.9×0.2=$
$8×1.2=$
$20×1.4=$
$2.2×0.6=$
$1.3×0.6=$
$0.25×0.04=$
$3.7×0.2=$
$40×1.3=$
$4.1×0.7=$
$2.4×5=$
$4.8×0.2=$
$70×0.1=$

$3.2×0.4=1.28$
$1.2×0.7=0.84$
$0.125×0.8=0.1$
$2.9×0.2=0.58$
$8×1.2=9.6$
$20×1.4=28$
$2.2×0.6=1.32$
$1.3×0.6=0.78$
$0.25×0.04=0.01$
$3.7×0.2=0.74$
$40×1.3=52$
$4.1×0.7=2.87$
$2.4×5=12$
$4.8×0.2=0.96$
$70×0.1=7$

2. 在$◯$里填上“$＞$”“$＜$”或“$=$”。
$50×1.01◯50$
$76.1×0.8◯2.1×76.1$
$1×3.3◯3.3$
$0.89×90◯8.9×9$
$3×0.78◯0.78$
$100×0.9◯9×10$
$0.8×0.8◯0.8$
$0.37×0.3◯3.7×0.3$

$50×1.01＞50$
$76.1×0.8＜2.1×76.1$
$1×3.3=3.3$
$0.89×90=8.9×9$
$3×0.78＞0.78$
$100×0.9=9×10$
$0.8×0.8＜0.8$
$0.37×0.3＜3.7×0.3$

3. 列竖式计算。
$12.39 + 8.25 =$
$15 - 10.26 =$
$0.25×0.64 =$

12.39
+ 8.25
-------
20.64
$12.39 + 8.25 = 20.64$
15.00
10.26
-------
4.74
$15 - 10.26 = 4.74$
0.25
× 0.64
--------
100
150
--------
0.1600
$0.25×0.64 = 0.16$

4. 计算下列各题，能简算的要简算。
$23.92 - (13.92 + 8.45)$
$23.92 - (13.92 - 8.45)$
$8.8×1.25 - 0.8×1.25$
$0.46×3.3 + 5.4×0.33$

$23.92 - (13.92 + 8.45)$
$=23.92 - 13.92 - 8.45$
$=10 - 8.45$
$=1.55$
$23.92 - (13.92 - 8.45)$
$=23.92 - 13.92 + 8.45$
$=10 + 8.45$
$=18.45$
$8.8×1.25 - 0.8×1.25$
$=(8.8 - 0.8)×1.25$
$=8×1.25$
$=10$
$0.46×3.3 + 5.4×0.33$
$=0.46×3.3 + 0.54×3.3$
$=(0.46 + 0.54)×3.3$
$=1×3.3$
$=3.3$