Latest Capgemini Aptitude Question SOLUTION: Calculate the sum of the series 5 + 55 + 555 + ……..+ n a) (10n – 1) – (5/9)n b) 50/81(10n – 1) – (5/9)n c) 50/81(10n – 1) – (5/9) d) (10n – 1) – (5/9)5n

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(#M40153740) CAPGEMINI Numerical Ability question Keep an EYE

Calculate the sum of the series

5 + 55 + 555 + ……..+ n

a) (10n – 1) – (5/9)n b) 50/81(10n – 1) – (5/9)n c) 50/81(10n – 1) – (5/9) d) (10n – 1) – (5/9)5n

Asked In Capgemini Ashton (8 years ago)

Unsolved Read Solution (4)

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jagadeesh  (8 years ago)

5+55+555+.............+n fives
5(1+11+111+1111+.............+n ones)
5/9(9+99+999+............+n nines)
5/9(10-1+100-1+1000-1+..............+10^n-1)
5/9((10+10^2+10^3+........+10^n)-n)
Geometric progression formula:-a(r^n-1/r-1)
5/9((10(10^n-1/10-1))-n)
50/81(10^n - 1)-(5/9)n

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krati  (8 years ago)

5+55+555+5555+⋯+55…5n fives
=5/9(1*9+11*9+111*9.....
=5/9(9+99+999+9999+⋯+99…9
=5/9(10−1+10^2−1+10^3−1+⋯+10^n−1)
=5/9(10^1+10^2+10^3+⋯+10^n−n)
=5/9((10^n+1−10)/9)−n).

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kshitij  (8 years ago)

5+55+555+5555+⋯+55…5n fives
=59(9+99+999+9999+⋯+99…9n nines)
=59(10−1+102−1+103−1+⋯+10n−1)
=59(101+102+103+⋯+10n−n)
=59(10n+1−109−n).

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saijyothi swaroop  (8 years ago)

try verification, you can get easily

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