1. 选择。(把正确答案的序号填在括号里。)
(1)计算$2.8×9.9$的简便方法是()。
①$2.8×9×0.1$ ②$2.8×10 - 2.8×0.1$ ③$2.8×10 - 0.1$
(2)计算$1.25×24×2.5$的简便方法是()。
①$24×1.25×2.5$ ②$1.25×8 + 2.5×3$ ③$(1.25×8)×(2.5×3)$
(3)$44×2.2 = 96.8$,则$4.4×220 = $()。
①$96.8$ ②$9.68$ ③$968$
(4)$5.6÷0.013$的计算结果是()。
①$430……0.01$ ②$43……0.01$ ③$430……10$
(5)下面各题中,商最大的算式是()。
①$5.6÷0.124$ ②$56÷12.4$ ③$5.6÷12.4$

②
③
③
①
①

(1)②
(2)③
(3)③
(4)①
(5)①

2. 口算。
$1.25×0.8 = $ $0.28÷0.7 = $ $0.05×0.9 = $
$8.7×0.01 = $ $0.48÷0.04 = $ $1÷0.25 = $
$7.2×0.2 = $ $0.54÷0.6 = $ $2.8×0.3 = $

1
0.4
0.045
0.087
12
4
1.44
0.9
0.84
0.03
3
1.21
0.08
91
70

3. 计算。
(1)列竖式计算。(第三小题得数保留两位小数,第五小题请写出验算过程。)
$47.04÷5.6 = $ $3.28×2.7 = $ $0.764×1.2≈$
$52.92÷0.27 = $ $8÷1.28 = $
(2)计算下面各题。
$64.68÷2.8 + 4.9$ $18.62 - 0.56÷0.8$
$96.2 - 12.5×2.4$ $44.3×8 - 21.55$
(3)用简便方法计算。
$2.5×0.65×4$ $101×0.85$
$7.86×9.9 + 7.86×0.1$ $22×2.5$
$125×9.7 - 125×1.7$ $24.5×0.125×0.8$

8.4

8.856

0.92
=23.1+4.9
=28
=18.62-0.7
=17.92
=96.2-30
=66.2
=354.4-21.55
=332.85
=2.5×4×0.65
=10×0.65
=6.5
=(100+1)×0.85
=100×0.85+0.85
=85.85
=7.86×(9.9+0.1)
=7.86×10
=78.6
=(20+2)×2.5
=20×2.5+2×2.5
=50+5
=55

196
验算:
6.25

1.28
=125×(9.7-1.7)
=125×8
=1000
=24.5×(0.125×0.8)
=24.5×0.1
=2.45