怎样简便计算①9999×9999②25×96×125(3)77777×99999÷11111÷11111(4)33333×22222÷66666(5)5÷(7÷13)÷(13÷16)÷(16÷19)÷(19÷21)(6)2008×2006-2009×2005

Answer 1

(1)9999×9999 (2)25×96×125 (3)77777×99999÷11111÷11111
=9999×(10000-1) =25×4×8×125×3 =77777×(100000-1)
=9999×10000-9999 =100×1000×3 =77777×100000-77777
=99990000-9999 =300000 =7777700000-77777
=99980001 =7777622223
(4)33333×22222÷66666 (5) 5÷(7÷13)÷(13÷16)÷(16÷19)÷(19÷21)
=33333×(22222÷66666) =5×13/7×16/13×19/16×21/19
=33333×1/3 =15
=11111
(6)2008×2006-2009×2005
=(2000+8)×2006-(2000+9)×2005
=2000×2006+8×2006-2000×2005-9×2005
=2000×(2006-2005)+8×2006-9×2005
=2000+8×(2000+6)-9×(2000+5)
=2000+8×2000+8×6-9×2000-9×5
=2000-2000×(9-8)+8×6-9×5
=2000-2000+48-45
=48-45
=3
第（3）题算错了,重做如下
(3)77777×99999÷11111÷11111
＝（77777÷11111）×（99999÷11111）
＝7×9
＝63