1.根据运算律填空。
0.41×3.02=×
16.2×0.25×0.4=×(×)
2.1×1.25×0.8=×(×)
6.7×8.9+3.3×8.9=(+)×

1. 0.41×3.02=0.41×3.02
16.2×0.25×0.4=16.2×(0.25×0.4)
2.1×1.25×0.8=2.1×(1.25×0.8)
6.7×8.9+3.3×8.9=(6.7+3.3)×8.9

2.用简便方法计算下面各题。
$4×0.8×2.5×12.5$
$(0.4+40)×25$
$2.5×16.7-2.5×0.7$
$0.32×0.25×1.25$
$9.9×5.4+0.54$
$80.8×12.5$

$4×0.8×2.5×12.5$
$=4×2.5×0.8×12.5$
$=(4×2.5)×(0.8×12.5)$
$=10×10$
$=100$
$(0.4+40)×25$
$=0.4×25+40×25$
$=10+1000$
$=1010$
$2.5×16.7-2.5×0.7$
$=2.5×(16.7-0.7)$
$=2.5×16$
$=40$
$0.32×0.25×1.25$
$=0.4×0.8×0.25×1.25$
$=0.4×0.25×0.8×1.25$
$=(0.4×0.25)×(0.8×1.25)$
$=0.1×1$
$=0.1$
$9.9×5.4+0.54$
$=9.9×5.4+0.1×5.4$
$=(9.9+0.1)×5.4$
$=10×5.4$
$=54$
$80.8×12.5$
$=(80+0.8)×12.5$
$=80×12.5+0.8×12.5$
$=1000+10$
$=1010$