1,、0.4×125×25×0.8

=（0.4×25）×（125×0.8)

=10×100

=1000

2、1.25×（8 10）

=1.25×8 1.25×10

=10 12.5

=22.5

3,、9123-（123 8.8）

=9123-123-8.8

=9000-8.8

=8991.2

4、1.24×8.3 8.3×1.76

=8.3×（1.24 1.76)

=8.3×3=24.9

5,、9999×1001

=9999×（1000 1）

=9999×1000 9999×1

=10008999

6,、14.8×6.3-6.3×6.5＋8.3×3.7

=（14.8-6.5）×6.3＋8.3×3.7

=8.3×6.3 8.3×3.7

8.3×（6.3＋3.7）

=8.3×10

=83

7、1.24 0.78 8.76

=（1.24 8.76） 0.78

=10 0.78

=10.78

8,、933-157-43

=933-（157 43）

=933-200

=733

9,、4821-998

=4821-1000 2

=3823

10、 I32×125×25

=4×8×125×25

=（4×25）×（8×125）

=100×1000

=100000

11,、9048÷268

=（2600 2600 2600 1248）÷26

=2600÷26 2600÷26 2600÷26 1248÷269

=100 100 100 48

=348

12,、2881÷ 43

=（1290 1591）÷ 434

=1290÷43 1591÷43

=30 37

13、3.2×42.3×3.75-12.5×0.423×16

=3.2×42.3×3.75-1.25×42.3×1.6

=42.3×(3.2×3.75-1.25×1.6)

=42.3×(4×0.8×3.75-1.25×4×0.4)

=42.3×(4×0.4×2×3.75-1.25×4×0.4)

=42.3×(4x0.4x7.5-1.25x4x0.4)

=42.3×[4×0.4×(7.5-1.25)]

=42.3×[4×0.4×6.25]

=42.3×(4×2.5)

=4237

14,、1.8 18÷1.5-0.5×0.3

=1.8 12-0.15

=13.8-0.15

=13.65

15,、6.5×8 3.5×8-47

=52 28-47

=80-47

16、(80-9.8)×2/5-1.32

=70.2X2/5-1.32

=28.08-1.32

=26.76

17,、8×4/7÷[1÷(3.2-2.95)]

=8×4/7÷[1÷0.25]

=8×4/7÷4

=8/7

18,、2700×（506－499）÷900

=2700×7÷900

=18900÷900

=21

19、33.02－（148.4－90.85）÷2.5

=33.02－57.55÷2.5

=33.02－23.02

=10

20,、（1÷1－1）÷5.1

=（1－1）÷5.1

=0÷5.1

=0

21,、1.24 0.78 8.76

=(1.24 8.76) 0.78

=10 0.78

=10.78

22、1/2-(4/5-1/2)

=1/2 1/2-4/5

=1-4/5

=1/5

23,、4800÷25÷4

=4800÷(25x4)

=4800÷100

=4800÷100

=48

24,、2/5-(3/8-3/5)

=2/5 3/5-3/8

=1-3/8

=5/8

25、3/4-(3/7-1/4)

=3/4 1/4-3/7

=1-3/7

=4/7

26,、3.2x0.125x2.5

=0.125x8x(0.4x2.5)

=1x1

=1

27,、0.4×125×25×0.8

=(0.4×25)×(125×0.8)

=10×100

=1000

28、1.25×(8 10)

=1.25×8 1.25×10

=10 12.5

=22.5

29,、9123-(123 8.8)

=9123-123-8.8

=9000-8.8

=8991.2

30,、9999×1001

=9999×(1000 1)

=9999×1000 9999×1

=10008999