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(#M40038897) TCS Numerical Ability question Keep an EYE

sum of terms 1*2 + 2*2^2 + 3*2^3 4*2^4 +..........+100*2^100 = ?

Asked In TCS hima (10 years ago)

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Read Solution (2) :

RAKESH  (10 years ago)

S = 1*2 + 2*2^2 + 3*2^3 + 4*2^4 .......+ 100*2^100
(-)2*S= 1*2^2 + 2*2^3 + .......+ 99*2^100 + 100*2^101
-------------------------------------------------------
=> S-2S = 2+2^2+2^3+2^4+.........+2^100-100*2^101
=> -S = 2*(2^100-1)/(2-1) - 100*2^101
=> S = 100*2^101 - 2*(2^100-1)
=> S = 100*2^101 - 2^101 + 2
=> S = 99*2^101 + 2

Is this solution Helpfull? Yes (24) | No (1)  

Ayush Jain  (10 years ago)

@rakesh 98*2^101+2.

Is this solution Helpfull? Yes | No (6)  

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