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(#M40029046) TCS question unsolved Keep an EYE

1-2+3-.................-100 find the value

Asked In TCS subhrajit mitra (11 years ago)

Unsolved Read Solution (7)

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Shishir kumar  (11 years ago)

1-2+3-4.....+99-100 ,this is the sequence
now, we divide the series into 2 groups..

(1+3+5+7...+99)-(2+4+6+8...+100)
using A.P sum formula,
(1+3+5...+99)=50/2(1+99) [s(n)=n/2(a+l)]
=2500
again for another sequence
(2+4+6...+100)=50/2(2+100)
=2550
the original sequence was=(1+3+5+7...+99)-(2+4+6...+100)
= 2500-2550
= -50 (ans).

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vibhumishra  (11 years ago)

1-2=-1
3-4=-1..... similarly -1-1.....50times=-50

Is this solution Helpfull? Yes (9) | No (1)  

Manjula  (11 years ago)

divide the sequence into 2 groups
sum of odd numbers =n*n (n=number of odd numbers)=2500
sum of even numbers =(n+1)*n (n=number of even numbers)=2550
ans is 2500-2550=-50

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parvez sajjad  (11 years ago)

it will be-50

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Guru Pranav  (11 years ago)

-50

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Shashi nath jha  (11 years ago)

-50 ans...

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parvez sajjad  (11 years ago)

ans=-50
...50*(-1)

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