self Maths Puzzle

From number 1 to 1666, all 6 replaced by 1 means, How many 1's are there?

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self Other Question

10=10
-10=-10
1-11=100-110
adding(11/2)^2
1-11+(11/2)^2=100-110+(11/2)^2
(1)^2-2*11/2*1+(11/2)^2=(10)^2-2*11/2*10+(11/2)^2
using identity
(a-b)^2=a^2+b^2-2ab
(1-11/2)^2=(10-11/2)^2
1-11/2=10-11/2
1=10

it is wrong or right
if it is wrong then why? 3 persons with odds in favour each are 2:3, 5:1, 5:7. Find the probability that majority of persons is in favour.