Question

简便计算; 1.9+1.99+1.999+1.9999+1.99999 28*1111+9999*8

Answer 1

1.9+1.99+1.999+1.9999+1.99999
= 2-0.1 + 2-0.01 + 2- 0.001 +2- 0.0001 +2- 0.00001
= 10- 0.11111
= 9.99999

28*1111+9999*8
= 28*1111+ 1111*9*8
= 1111*(28+72)
= 1111*100
= 111100
秋风燕燕为您答题 O(∩_∩)O
有什么不明白可以对该题继续追问
如果满意，请及时选为满意答案，谢谢

追问

为什么和上面的答案不一样？

追答

不好意思。。。第一题是我大意了，最后一步，算错了
1.9+1.99+1.999+1.9999+1.99999
= 2-0.1 + 2-0.01 + 2- 0.001 +2- 0.0001 +2- 0.00001
= 10- 0.11111
= 9.88889
真的不好意思 O(∩_∩)O

追问

第一题我不明白什么意思

Answer 2

1.9+1.99+1.999+1.9999+1.99999
= 2-0.1 + 2-0.01 + 2- 0.001 +2- 0.0001 +2- 0.00001
= 10- 0.11111
= 9.88889

28*1111+9999*8
= 28*1111+ 1111*9*8
= 1111*(28+72)
= 1111*100
= 111100

Answer 3

1.9+1.99+1.999+1.9999+1.99999
解：=2+2+2+2+2-0.1-0.01-0.001-0.0001-0.00001
=10-0.11111
=9.88889
28*1111+9999*8
解：=28÷9×1111×9+9999×8
=28/9×9999+9999×8
=（28/9+8）×9999
=100/9×9999
=111100

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