1. 直接写出得数。
$810÷30=$ $0.56×0.4=$ $12.6+5.7=$
$5.6-3.7=$ $25×4÷25×4=$ $2.4+24.5=$
$1.7×0.4=$ $56÷100=$ $12.6÷100=$
$24+6.6=$ $2.86-0.8=$ $2.1+1.17=$

$810÷30=27$
$0.56×0.4=0.224$
$12.6+5.7=18.3$
$5.6-3.7=1.9$
$25×4÷25×4=16$
$2.4+24.5=26.9$
$1.7×0.4=0.68$
$56÷100=0.56$
$12.6÷100=0.126$
$24+6.6=30.6$
$2.86-0.8=2.06$
$2.1+1.17=3.27$

2. 计算下列各题，能简算的要简算。
$12.5×3.3×0.8$ $99×4.8$ $0.87×6.6+0.87×3.4$
$2.5×32×12.5$ $23.5×201-23.5$ $(1.25-0.125)×80$
$0.25×3.6×4$ $12.8×13.7-12.8×3.7$ $36÷6×2.4$
$32.5-1.25+8$ $(3.2+0.56)×0.4$ $21.4-20.5+8.2$

12.5×3.3×0.8
=12.5×0.8×3.3
=10×3.3
=33
99×4.8
=(100-1)×4.8
=100×4.8 -1×4.8
=480 -4.8
=475.2
0.87×6.6+0.87×3.4
=0.87×(6.6+3.4)
=0.87×10
=8.7
2.5×32×12.5
=2.5×(4×8)×12.5
=(2.5×4)×(8×12.5)
=10×100
=1000
23.5×201-23.5
=23.5×(201-1)
=23.5×200
=4700
(1.25-0.125)×80
=1.25×80 -0.125×80
=100 -10
=90
0.25×3.6×4
=0.25×4×3.6
=1×3.6
=3.6
12.8×13.7-12.8×3.7
=12.8×(13.7-3.7)
=12.8×10
=128
36÷6×2.4
=6×2.4
=14.4
32.5-1.25+8
=31.25+8
=39.25
(3.2+0.56)×0.4
=3.2×0.4 +0.56×0.4
=1.28 +0.224
=1.504
21.4-20.5+8.2
=0.9+8.2
=9.1